CINXE.COM

<!DOCTYPE html> <html class="client-nojs vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-sticky-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-toc-available" lang="en" dir="ltr"> <head> <meta charset="UTF-8"> <title>Two-empire system - Wikipedia</title> <script>(function(){var className="client-js vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-sticky-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-toc-available";var cookie=document.cookie.match(/(?:^|; )enwikimwclientpreferences=([^;]+)/);if(cookie){cookie[1].split('%2C').forEach(function(pref){className=className.replace(new RegExp('(^| )'+pref.replace(/-clientpref-\w+$|[^\w-]+/g,'')+'-clientpref-\\w+( |$)'),'$1'+pref+'$2');});}document.documentElement.className=className;}());RLCONF={"wgBreakFrames":false,"wgSeparatorTransformTable":["",""],"wgDigitTransformTable":["",""],"wgDefaultDateFormat":"dmy", "wgMonthNames":["","January","February","March","April","May","June","July","August","September","October","November","December"],"wgRequestId":"1f25a23e-b306-49ee-8a61-180c781d18c5","wgCanonicalNamespace":"","wgCanonicalSpecialPageName":false,"wgNamespaceNumber":0,"wgPageName":"Two-empire_system","wgTitle":"Two-empire system","wgCurRevisionId":1253240956,"wgRevisionId":1253240956,"wgArticleId":1591801,"wgIsArticle":true,"wgIsRedirect":false,"wgAction":"view","wgUserName":null,"wgUserGroups":["*"],"wgCategories":["CS1: long volume value","Articles with short description","Short description is different from Wikidata","High-level systems of taxonomy"],"wgPageViewLanguage":"en","wgPageContentLanguage":"en","wgPageContentModel":"wikitext","wgRelevantPageName":"Two-empire_system","wgRelevantArticleId":1591801,"wgIsProbablyEditable":true,"wgRelevantPageIsProbablyEditable":true,"wgRestrictionEdit":[],"wgRestrictionMove":[],"wgNoticeProject":"wikipedia","wgCiteReferencePreviewsActive":false, "wgFlaggedRevsParams":{"tags":{"status":{"levels":1}}},"wgMediaViewerOnClick":true,"wgMediaViewerEnabledByDefault":true,"wgPopupsFlags":0,"wgVisualEditor":{"pageLanguageCode":"en","pageLanguageDir":"ltr","pageVariantFallbacks":"en"},"wgMFDisplayWikibaseDescriptions":{"search":true,"watchlist":true,"tagline":false,"nearby":true},"wgWMESchemaEditAttemptStepOversample":false,"wgWMEPageLength":3000,"wgRelatedArticlesCompat":[],"wgCentralAuthMobileDomain":false,"wgEditSubmitButtonLabelPublish":true,"wgULSPosition":"interlanguage","wgULSisCompactLinksEnabled":false,"wgVector2022LanguageInHeader":true,"wgULSisLanguageSelectorEmpty":false,"wgWikibaseItemId":"Q3324187","wgCheckUserClientHintsHeadersJsApi":["brands","architecture","bitness","fullVersionList","mobile","model","platform","platformVersion"],"GEHomepageSuggestedEditsEnableTopics":true,"wgGETopicsMatchModeEnabled":false,"wgGEStructuredTaskRejectionReasonTextInputEnabled":false,"wgGELevelingUpEnabledForUser":false};RLSTATE={ "ext.globalCssJs.user.styles":"ready","site.styles":"ready","user.styles":"ready","ext.globalCssJs.user":"ready","user":"ready","user.options":"loading","ext.cite.styles":"ready","skins.vector.search.codex.styles":"ready","skins.vector.styles":"ready","skins.vector.icons":"ready","ext.wikimediamessages.styles":"ready","ext.visualEditor.desktopArticleTarget.noscript":"ready","ext.uls.interlanguage":"ready","wikibase.client.init":"ready","ext.wikimediaBadges":"ready"};RLPAGEMODULES=["ext.cite.ux-enhancements","mediawiki.page.media","site","mediawiki.page.ready","skins.vector.js","ext.centralNotice.geoIP","ext.centralNotice.startUp","ext.gadget.ReferenceTooltips","ext.gadget.switcher","ext.urlShortener.toolbar","ext.centralauth.centralautologin","mmv.bootstrap","ext.popups","ext.visualEditor.desktopArticleTarget.init","ext.visualEditor.targetLoader","ext.echo.centralauth","ext.eventLogging","ext.wikimediaEvents","ext.navigationTiming","ext.uls.interface","ext.cx.eventlogging.campaigns", "ext.cx.uls.quick.actions","wikibase.client.vector-2022","ext.checkUser.clientHints","ext.quicksurveys.init","ext.growthExperiments.SuggestedEditSession","wikibase.sidebar.tracking"];</script> <script>(RLQ=window.RLQ||[]).push(function(){mw.loader.impl(function(){return["user.options@12s5i",function($,jQuery,require,module){mw.user.tokens.set({"patrolToken":"+\\","watchToken":"+\\","csrfToken":"+\\"}); }];});});</script> <link rel="stylesheet" href="/w/load.php?lang=en&modules=ext.cite.styles%7Cext.uls.interlanguage%7Cext.visualEditor.desktopArticleTarget.noscript%7Cext.wikimediaBadges%7Cext.wikimediamessages.styles%7Cskins.vector.icons%2Cstyles%7Cskins.vector.search.codex.styles%7Cwikibase.client.init&only=styles&skin=vector-2022"> <script async="" src="/w/load.php?lang=en&modules=startup&only=scripts&raw=1&skin=vector-2022"></script> <meta name="ResourceLoaderDynamicStyles" content=""> <link rel="stylesheet" href="/w/load.php?lang=en&modules=site.styles&only=styles&skin=vector-2022"> <meta name="generator" content="MediaWiki 1.44.0-wmf.4"> <meta name="referrer" content="origin"> <meta name="referrer" content="origin-when-cross-origin"> <meta name="robots" content="max-image-preview:standard"> <meta name="format-detection" content="telephone=no"> <meta property="og:image" content="https://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Tree_of_Living_Organisms_2.png/1200px-Tree_of_Living_Organisms_2.png"> <meta property="og:image:width" content="1200"> <meta property="og:image:height" content="1202"> <meta property="og:image" content="https://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Tree_of_Living_Organisms_2.png/800px-Tree_of_Living_Organisms_2.png"> <meta property="og:image:width" content="800"> <meta property="og:image:height" content="802"> <meta property="og:image" content="https://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Tree_of_Living_Organisms_2.png/640px-Tree_of_Living_Organisms_2.png"> <meta property="og:image:width" content="640"> <meta property="og:image:height" content="641"> <meta name="viewport" content="width=1120"> <meta property="og:title" content="Two-empire system - Wikipedia"> <meta property="og:type" content="website"> <link rel="preconnect" href="//upload.wikimedia.org"> <link rel="alternate" media="only screen and (max-width: 640px)" href="//en.m.wikipedia.org/wiki/Two-empire_system"> <link rel="alternate" type="application/x-wiki" title="Edit this page" href="/w/index.php?title=Two-empire_system&action=edit"> <link rel="apple-touch-icon" href="/static/apple-touch/wikipedia.png"> <link rel="icon" href="/static/favicon/wikipedia.ico"> <link rel="search" type="application/opensearchdescription+xml" href="/w/rest.php/v1/search" title="Wikipedia (en)"> <link rel="EditURI" type="application/rsd+xml" href="//en.wikipedia.org/w/api.php?action=rsd"> <link rel="canonical" href="https://en.wikipedia.org/wiki/Two-empire_system"> <link rel="license" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en"> <link rel="alternate" type="application/atom+xml" title="Wikipedia Atom feed" href="/w/index.php?title=Special:RecentChanges&feed=atom"> <link rel="dns-prefetch" href="//meta.wikimedia.org" /> <link rel="dns-prefetch" href="//login.wikimedia.org"> </head> <body class="skin--responsive skin-vector skin-vector-search-vue mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject mw-editable page-Two-empire_system rootpage-Two-empire_system skin-vector-2022 action-view"><a class="mw-jump-link" href="#bodyContent">Jump to content</a> <div class="vector-header-container"> <header class="vector-header mw-header"> <div class="vector-header-start"> <nav class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-dropdown" class="vector-dropdown vector-main-menu-dropdown vector-button-flush-left vector-button-flush-right" > <input type="checkbox" id="vector-main-menu-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-main-menu-dropdown" class="vector-dropdown-checkbox " aria-label="Main menu" > <label id="vector-main-menu-dropdown-label" for="vector-main-menu-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-menu mw-ui-icon-wikimedia-menu"></span> <span class="vector-dropdown-label-text">Main menu</span> </label> <div class="vector-dropdown-content"> <div id="vector-main-menu-unpinned-container" class="vector-unpinned-container"> <div id="vector-main-menu" class="vector-main-menu vector-pinnable-element"> <div class="vector-pinnable-header vector-main-menu-pinnable-header vector-pinnable-header-unpinned" data-feature-name="main-menu-pinned" data-pinnable-element-id="vector-main-menu" data-pinned-container-id="vector-main-menu-pinned-container" data-unpinned-container-id="vector-main-menu-unpinned-container" > <div class="vector-pinnable-header-label">Main menu</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-main-menu.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-main-menu.unpin">hide</button> </div> <div id="p-navigation" class="vector-menu mw-portlet mw-portlet-navigation" > <div class="vector-menu-heading"> Navigation </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="n-mainpage-description" class="mw-list-item"><a href="/wiki/Main_Page" title="Visit the main page [z]" accesskey="z"><span>Main page</span></a></li><li id="n-contents" class="mw-list-item"><a href="/wiki/Wikipedia:Contents" title="Guides to browsing Wikipedia"><span>Contents</span></a></li><li id="n-currentevents" class="mw-list-item"><a href="/wiki/Portal:Current_events" title="Articles related to current events"><span>Current events</span></a></li><li id="n-randompage" class="mw-list-item"><a href="/wiki/Special:Random" title="Visit a randomly selected article [x]" accesskey="x"><span>Random article</span></a></li><li id="n-aboutsite" class="mw-list-item"><a href="/wiki/Wikipedia:About" title="Learn about Wikipedia and how it works"><span>About Wikipedia</span></a></li><li id="n-contactpage" class="mw-list-item"><a href="//en.wikipedia.org/wiki/Wikipedia:Contact_us" title="How to contact Wikipedia"><span>Contact us</span></a></li> </ul> </div> </div> <div id="p-interaction" class="vector-menu mw-portlet mw-portlet-interaction" > <div class="vector-menu-heading"> Contribute </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="n-help" class="mw-list-item"><a href="/wiki/Help:Contents" title="Guidance on how to use and edit Wikipedia"><span>Help</span></a></li><li id="n-introduction" class="mw-list-item"><a href="/wiki/Help:Introduction" title="Learn how to edit Wikipedia"><span>Learn to edit</span></a></li><li id="n-portal" class="mw-list-item"><a href="/wiki/Wikipedia:Community_portal" title="The hub for editors"><span>Community portal</span></a></li><li id="n-recentchanges" class="mw-list-item"><a href="/wiki/Special:RecentChanges" title="A list of recent changes to Wikipedia [r]" accesskey="r"><span>Recent changes</span></a></li><li id="n-upload" class="mw-list-item"><a href="/wiki/Wikipedia:File_upload_wizard" title="Add images or other media for use on Wikipedia"><span>Upload file</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> <a href="/wiki/Main_Page" class="mw-logo"> <img class="mw-logo-icon" src="/static/images/icons/wikipedia.png" alt="" aria-hidden="true" height="50" width="50"> <span class="mw-logo-container skin-invert"> <img class="mw-logo-wordmark" alt="Wikipedia" src="/static/images/mobile/copyright/wikipedia-wordmark-en.svg" style="width: 7.5em; height: 1.125em;"> <img class="mw-logo-tagline" alt="The Free Encyclopedia" src="/static/images/mobile/copyright/wikipedia-tagline-en.svg" width="117" height="13" style="width: 7.3125em; height: 0.8125em;"> </span> </a> </div> <div class="vector-header-end"> <div id="p-search" role="search" class="vector-search-box-vue vector-search-box-collapses vector-search-box-show-thumbnail vector-search-box-auto-expand-width vector-search-box"> <a href="/wiki/Special:Search" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only search-toggle" title="Search Wikipedia [f]" accesskey="f"><span class="vector-icon mw-ui-icon-search mw-ui-icon-wikimedia-search"></span> <span>Search</span> </a> <div class="vector-typeahead-search-container"> <div class="cdx-typeahead-search cdx-typeahead-search--show-thumbnail cdx-typeahead-search--auto-expand-width"> <form action="/w/index.php" id="searchform" class="cdx-search-input cdx-search-input--has-end-button"> <div id="simpleSearch" class="cdx-search-input__input-wrapper" data-search-loc="header-moved"> <div class="cdx-text-input cdx-text-input--has-start-icon"> <input class="cdx-text-input__input" type="search" name="search" placeholder="Search Wikipedia" aria-label="Search Wikipedia" autocapitalize="sentences" title="Search Wikipedia [f]" accesskey="f" id="searchInput" > <span class="cdx-text-input__icon cdx-text-input__start-icon"></span> </div> <input type="hidden" name="title" value="Special:Search"> </div> <button class="cdx-button cdx-search-input__end-button">Search</button> </form> </div> </div> </div> <nav class="vector-user-links vector-user-links-wide" aria-label="Personal tools"> <div class="vector-user-links-main"> <div id="p-vector-user-menu-preferences" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-userpage" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-dropdown" class="vector-dropdown " title="Change the appearance of the page's font size, width, and color" > <input type="checkbox" id="vector-appearance-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-appearance-dropdown" class="vector-dropdown-checkbox " aria-label="Appearance" > <label id="vector-appearance-dropdown-label" for="vector-appearance-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-appearance mw-ui-icon-wikimedia-appearance"></span> <span class="vector-dropdown-label-text">Appearance</span> </label> <div class="vector-dropdown-content"> <div id="vector-appearance-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <div id="p-vector-user-menu-notifications" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-overflow" class="vector-menu mw-portlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="https://donate.wikimedia.org/wiki/Special:FundraiserRedirector?utm_source=donate&utm_medium=sidebar&utm_campaign=C13_en.wikipedia.org&uselang=en" class=""><span>Donate</span></a> </li> <li id="pt-createaccount-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:CreateAccount&returnto=Two-empire+system" title="You are encouraged to create an account and log in; however, it is not mandatory" class=""><span>Create account</span></a> </li> <li id="pt-login-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:UserLogin&returnto=Two-empire+system" title="You're encouraged to log in; however, it's not mandatory. [o]" accesskey="o" class=""><span>Log in</span></a> </li> </ul> </div> </div> </div> <div id="vector-user-links-dropdown" class="vector-dropdown vector-user-menu vector-button-flush-right vector-user-menu-logged-out" title="Log in and more options" > <input type="checkbox" id="vector-user-links-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-user-links-dropdown" class="vector-dropdown-checkbox " aria-label="Personal tools" > <label id="vector-user-links-dropdown-label" for="vector-user-links-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-ellipsis mw-ui-icon-wikimedia-ellipsis"></span> <span class="vector-dropdown-label-text">Personal tools</span> </label> <div class="vector-dropdown-content"> <div id="p-personal" class="vector-menu mw-portlet mw-portlet-personal user-links-collapsible-item" title="User menu" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport" class="user-links-collapsible-item mw-list-item"><a href="https://donate.wikimedia.org/wiki/Special:FundraiserRedirector?utm_source=donate&utm_medium=sidebar&utm_campaign=C13_en.wikipedia.org&uselang=en"><span>Donate</span></a></li><li id="pt-createaccount" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Special:CreateAccount&returnto=Two-empire+system" title="You are encouraged to create an account and log in; however, it is not mandatory"><span class="vector-icon mw-ui-icon-userAdd mw-ui-icon-wikimedia-userAdd"></span> <span>Create account</span></a></li><li id="pt-login" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Special:UserLogin&returnto=Two-empire+system" title="You're encouraged to log in; however, it's not mandatory. [o]" accesskey="o"><span class="vector-icon mw-ui-icon-logIn mw-ui-icon-wikimedia-logIn"></span> <span>Log in</span></a></li> </ul> </div> </div> <div id="p-user-menu-anon-editor" class="vector-menu mw-portlet mw-portlet-user-menu-anon-editor" > <div class="vector-menu-heading"> Pages for logged out editors <a href="/wiki/Help:Introduction" aria-label="Learn more about editing"><span>learn more</span></a> </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-anoncontribs" class="mw-list-item"><a href="/wiki/Special:MyContributions" title="A list of edits made from this IP address [y]" accesskey="y"><span>Contributions</span></a></li><li id="pt-anontalk" class="mw-list-item"><a href="/wiki/Special:MyTalk" title="Discussion about edits from this IP address [n]" accesskey="n"><span>Talk</span></a></li> </ul> </div> </div> </div> </div> </nav> </div> </header> </div> <div class="mw-page-container"> <div class="mw-page-container-inner"> <div class="vector-sitenotice-container"> <div id="siteNotice"></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Contents" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Contents</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Two-empire system</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 7 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-7" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">7 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%86%D8%B8%D8%A7%D9%85_%D8%A7%D9%84%D8%A5%D9%85%D8%A8%D8%B1%D8%A7%D8%B7%D9%88%D8%B1%D9%8A%D8%AA%D8%A7%D9%86" title="نظام الإمبراطوريتان – Arabic" lang="ar" hreflang="ar" data-title="نظام الإمبراطوريتان" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Kahe_%C3%BClemriigi_s%C3%BCsteem" title="Kahe ülemriigi süsteem – Estonian" lang="et" hreflang="et" data-title="Kahe ülemriigi süsteem" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Sistema_de_dos_superreinos" title="Sistema de dos superreinos – Spanish" lang="es" hreflang="es" data-title="Sistema de dos superreinos" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Empire_(biologie)" title="Empire (biologie) – French" lang="fr" hreflang="fr" data-title="Empire (biologie)" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Sistema_de_dous_imperios" title="Sistema de dous imperios – Galician" lang="gl" hreflang="gl" data-title="Sistema de dous imperios" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Sistema_dos_dois_imp%C3%A9rios" title="Sistema dos dois impérios – Portuguese" lang="pt" hreflang="pt" data-title="Sistema dos dois impérios" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-kab mw-list-item"><a href="https://kab.wikipedia.org/wiki/Amenkud_(tasnudert)" title="Amenkud (tasnudert) – Kabyle" lang="kab" hreflang="kab" data-title="Amenkud (tasnudert)" data-language-autonym="Taqbaylit" data-language-local-name="Kabyle" class="interlanguage-link-target"><span>Taqbaylit</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q3324187#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Two-empire_system" title="View the content page [c]" accesskey="c"><span>Article</span></a></li><li id="ca-talk" class="vector-tab-noicon mw-list-item"><a href="/wiki/Talk:Two-empire_system" rel="discussion" title="Discuss improvements to the content page [t]" accesskey="t"><span>Talk</span></a></li> </ul> </div> </div> <div id="vector-variants-dropdown" class="vector-dropdown emptyPortlet" > <input type="checkbox" id="vector-variants-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-variants-dropdown" class="vector-dropdown-checkbox " aria-label="Change language variant" > <label id="vector-variants-dropdown-label" for="vector-variants-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">English</span> </label> <div class="vector-dropdown-content"> <div id="p-variants" class="vector-menu mw-portlet mw-portlet-variants emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> </div> </div> </nav> </div> <div id="right-navigation" class="vector-collapsible"> <nav aria-label="Views"> <div id="p-views" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-views" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-view" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Two-empire_system"><span>Read</span></a></li><li id="ca-edit" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Two-empire_system&action=edit" title="Edit this page [e]" accesskey="e"><span>Edit</span></a></li><li id="ca-history" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Two-empire_system&action=history" title="Past revisions of this page [h]" accesskey="h"><span>View history</span></a></li> </ul> </div> </div> </nav> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-dropdown" class="vector-dropdown vector-page-tools-dropdown" > <input type="checkbox" id="vector-page-tools-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-tools-dropdown" class="vector-dropdown-checkbox " aria-label="Tools" > <label id="vector-page-tools-dropdown-label" for="vector-page-tools-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">Tools</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-tools-unpinned-container" class="vector-unpinned-container"> <div id="vector-page-tools" class="vector-page-tools vector-pinnable-element"> <div class="vector-pinnable-header vector-page-tools-pinnable-header vector-pinnable-header-unpinned" data-feature-name="page-tools-pinned" data-pinnable-element-id="vector-page-tools" data-pinned-container-id="vector-page-tools-pinned-container" data-unpinned-container-id="vector-page-tools-unpinned-container" > <div class="vector-pinnable-header-label">Tools</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-page-tools.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-page-tools.unpin">hide</button> </div> <div id="p-cactions" class="vector-menu mw-portlet mw-portlet-cactions emptyPortlet vector-has-collapsible-items" title="More options" > <div class="vector-menu-heading"> Actions </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-more-view" class="selected vector-more-collapsible-item mw-list-item"><a href="/wiki/Two-empire_system"><span>Read</span></a></li><li id="ca-more-edit" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Two-empire_system&action=edit" title="Edit this page [e]" accesskey="e"><span>Edit</span></a></li><li id="ca-more-history" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Two-empire_system&action=history"><span>View history</span></a></li> </ul> </div> </div> <div id="p-tb" class="vector-menu mw-portlet mw-portlet-tb" > <div class="vector-menu-heading"> General </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-whatlinkshere" class="mw-list-item"><a href="/wiki/Special:WhatLinksHere/Two-empire_system" title="List of all English Wikipedia pages containing links to this page [j]" accesskey="j"><span>What links here</span></a></li><li id="t-recentchangeslinked" class="mw-list-item"><a href="/wiki/Special:RecentChangesLinked/Two-empire_system" rel="nofollow" title="Recent changes in pages linked from this page [k]" accesskey="k"><span>Related changes</span></a></li><li id="t-upload" class="mw-list-item"><a href="/wiki/Wikipedia:File_Upload_Wizard" title="Upload files [u]" accesskey="u"><span>Upload file</span></a></li><li id="t-specialpages" class="mw-list-item"><a href="/wiki/Special:SpecialPages" title="A list of all special pages [q]" accesskey="q"><span>Special pages</span></a></li><li id="t-permalink" class="mw-list-item"><a href="/w/index.php?title=Two-empire_system&oldid=1253240956" title="Permanent link to this revision of this page"><span>Permanent link</span></a></li><li id="t-info" class="mw-list-item"><a href="/w/index.php?title=Two-empire_system&action=info" title="More information about this page"><span>Page information</span></a></li><li id="t-cite" class="mw-list-item"><a href="/w/index.php?title=Special:CiteThisPage&page=Two-empire_system&id=1253240956&wpFormIdentifier=titleform" title="Information on how to cite this page"><span>Cite this page</span></a></li><li id="t-urlshortener" class="mw-list-item"><a href="/w/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FTwo-empire_system"><span>Get shortened URL</span></a></li><li id="t-urlshortener-qrcode" class="mw-list-item"><a href="/w/index.php?title=Special:QrCode&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FTwo-empire_system"><span>Download QR code</span></a></li> </ul> </div> </div> <div id="p-coll-print_export" class="vector-menu mw-portlet mw-portlet-coll-print_export" > <div class="vector-menu-heading"> Print/export </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="coll-download-as-rl" class="mw-list-item"><a href="/w/index.php?title=Special:DownloadAsPdf&page=Two-empire_system&action=show-download-screen" title="Download this page as a PDF file"><span>Download as PDF</span></a></li><li id="t-print" class="mw-list-item"><a href="/w/index.php?title=Two-empire_system&printable=yes" title="Printable version of this page [p]" accesskey="p"><span>Printable version</span></a></li> </ul> </div> </div> <div id="p-wikibase-otherprojects" class="vector-menu mw-portlet mw-portlet-wikibase-otherprojects" > <div class="vector-menu-heading"> In other projects </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-wikibase" class="wb-otherproject-link wb-otherproject-wikibase-dataitem mw-list-item"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q3324187" title="Structured data on this page hosted by Wikidata [g]" accesskey="g"><span>Wikidata item</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> </div> </div> </div> <div class="vector-column-end"> <div class="vector-sticky-pinned-container"> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-pinned-container" class="vector-pinned-container"> </div> </nav> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-pinned-container" class="vector-pinned-container"> <div id="vector-appearance" class="vector-appearance vector-pinnable-element"> <div class="vector-pinnable-header vector-appearance-pinnable-header vector-pinnable-header-pinned" data-feature-name="appearance-pinned" data-pinnable-element-id="vector-appearance" data-pinned-container-id="vector-appearance-pinned-container" data-unpinned-container-id="vector-appearance-unpinned-container" > <div class="vector-pinnable-header-label">Appearance</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Biological classification system</div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Tree_of_Living_Organisms_2.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Tree_of_Living_Organisms_2.png/250px-Tree_of_Living_Organisms_2.png" decoding="async" width="250" height="250" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Tree_of_Living_Organisms_2.png/375px-Tree_of_Living_Organisms_2.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Tree_of_Living_Organisms_2.png/500px-Tree_of_Living_Organisms_2.png 2x" data-file-width="1530" data-file-height="1533" /></a><figcaption>Phylogenetic and symbiogenetic tree of living organisms, showing the origins of eukaryotes and prokaryotes</figcaption></figure> <p>The <b>two-empire system</b> (<b>two-superkingdom system</b>) was the top-level biological classification system in general use from the early 20th century until the establishment of the <a href="/wiki/Three-domain_system" title="Three-domain system">three-domain system</a> (which itself is currently being challenged by the <a href="/wiki/Two-domain_system" title="Two-domain system">two-domain system</a>). It classified cellular life into <a href="/wiki/Prokaryota" class="mw-redirect" title="Prokaryota">Prokaryota</a> and <a href="/wiki/Eukaryota" class="mw-redirect" title="Eukaryota">Eukaryota</a> as either "empires" or "superkingdoms". When the three-domain system was introduced, some biologists preferred the two-superkingdom system, claiming that the three-domain system overemphasized the division between <a href="/wiki/Archaea" title="Archaea">Archaea</a> and <a href="/wiki/Bacteria" title="Bacteria">Bacteria</a>. However, given the current state of knowledge and the rapid progress in biological scientific advancement, especially due to genetic analyses, that view has all but vanished. </p><p>Some prominent scientists, such as the late <a href="/wiki/Thomas_Cavalier-Smith" title="Thomas Cavalier-Smith">Thomas Cavalier-Smith</a>, still hold and held to the two-empire system.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The late <a href="/wiki/Ernst_Mayr" title="Ernst Mayr">Ernst Mayr</a>, one of the 20th century's leading evolutionary biologists, wrote dismissively of the three-domain system, "I cannot see any merit at all in a three empire cladification."<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> Additionally, the scientist <a href="/w/index.php?title=Radhey_Gupta_(biologist)&action=edit&redlink=1" class="new" title="Radhey Gupta (biologist) (page does not exist)">Radhey Gupta</a> argues for a return to the two-empire system, claiming that the primary division within prokaryotes should be among those surrounded by a single membrane (monoderm), including gram-positive bacteria and archaebacteria, and those with an inner and outer cell membrane (diderm), including gram-negative bacteria.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p><p>This system was preceded by <a href="/wiki/Ernst_Haeckel" title="Ernst Haeckel">Haeckel</a>'s <a href="/wiki/Kingdom_(biology)#Three_kingdoms" title="Kingdom (biology)">three-kingdom system</a>: <a href="/wiki/Animalia" class="mw-redirect" title="Animalia">Animalia</a>, <a href="/wiki/Plantae" class="mw-redirect" title="Plantae">Plantae</a> and <a href="/wiki/Protista" class="mw-redirect" title="Protista">Protista</a>. </p> <table style="margin-left: 0.5em; border-collapse: collapse;"> <tbody><tr> <th style="padding: 4px; border-bottom: solid black 1px;"><a href="/wiki/Carl_Linnaeus" title="Carl Linnaeus">Linnaeus</a><br />1735<sup id="cite_ref-Linnaeus1735_4-0" class="reference"><a href="#cite_note-Linnaeus1735-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </th> <th style="padding: 4px; border-bottom: solid black 1px;"><a href="/wiki/Ernst_Haeckel" title="Ernst Haeckel">Haeckel</a><br />1866<sup id="cite_ref-Haeckel_5-0" class="reference"><a href="#cite_note-Haeckel-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </th> <th style="padding: 4px; border-bottom: solid black 1px;"><a href="/wiki/%C3%89douard_Chatton" title="Édouard Chatton">Chatton</a><br />1925<sup id="cite_ref-Chatton1925_6-0" class="reference"><a href="#cite_note-Chatton1925-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Chatton_7-0" class="reference"><a href="#cite_note-Chatton-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </th> <th style="padding: 4px; border-bottom: solid black 1px;"><a href="/wiki/Herbert_Copeland_(biologist)" title="Herbert Copeland (biologist)">Copeland</a><br />1938<sup id="cite_ref-Copeland1938_8-0" class="reference"><a href="#cite_note-Copeland1938-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Copeland1956_9-0" class="reference"><a href="#cite_note-Copeland1956-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </th> <th style="padding: 4px; border-bottom: solid black 1px;"><a href="/wiki/Robert_Whittaker_(ecologist)" title="Robert Whittaker (ecologist)">Whittaker</a><br />1969<sup id="cite_ref-Whittaker1969_10-0" class="reference"><a href="#cite_note-Whittaker1969-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </th> <th style="padding: 4px; border-bottom: solid black 1px;"><a href="/wiki/Carl_Woese" title="Carl Woese">Woese</a> <i>et al</i>.<br />1977<sup id="cite_ref-Woese1977_11-0" class="reference"><a href="#cite_note-Woese1977-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Woese1977b_12-0" class="reference"><a href="#cite_note-Woese1977b-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </th> <th style="padding: 4px; border-bottom: solid black 1px;">Woese <i>et al.</i><br />1990<sup id="cite_ref-Woese1990_13-0" class="reference"><a href="#cite_note-Woese1990-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </th> <th style="padding: 4px; border-bottom: solid black 1px;"><a href="/wiki/Thomas_Cavalier-Smith" title="Thomas Cavalier-Smith">Cavalier-Smith</a><br />1993<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </th> <th style="padding: 4px; border-bottom: solid black 1px;">Cavalier-Smith<br />1998<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-CavalierSmith2004_18-0" class="reference"><a href="#cite_note-CavalierSmith2004-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-pmid20031978_19-0" class="reference"><a href="#cite_note-pmid20031978-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> </th> <th style="padding: 4px; border-bottom: solid black 1px;">Ruggiero <i>et al</i>.<br />2015<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> </th></tr> <tr> <td style="text-align: center; border-bottom: solid black 1px; padding-left: 4px; padding-right: 4px;">— </td> <td style="text-align: center; border-bottom: solid black 1px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;">— </td> <td style="text-align: center; border-bottom: solid black 1px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a class="mw-selflink selflink">2 empires</a> </td> <td style="text-align: center; border-bottom: solid black 1px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a class="mw-selflink selflink">2 empires</a> </td> <td style="text-align: center; border-bottom: solid black 1px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a class="mw-selflink selflink">2 empires</a> </td> <td style="text-align: center; border-bottom: solid black 1px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a class="mw-selflink selflink">2 empires</a> </td> <td style="text-align: center; border-bottom: solid black 1px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a href="/wiki/Three-domain_system" title="Three-domain system">3 domains</a> </td> <td style="text-align: center; border-bottom: solid black 1px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;">3 superkingdoms </td> <td style="text-align: center; border-bottom: solid black 1px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a class="mw-selflink selflink">2 empires</a> </td> <td style="text-align: center; border-bottom: solid black 1px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a class="mw-selflink selflink">2 superkingdoms</a> </td></tr> <tr> <td style="text-align: center; border-bottom: double black 3px; padding-left: 4px; padding-right: 4px;">2 kingdoms </td> <td style="text-align: center; border-bottom: double black 3px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;">3 kingdoms </td> <td style="text-align: center; border-bottom: double black 3px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;">— </td> <td style="text-align: center; border-bottom: double black 3px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a href="/wiki/Kingdom_(biology)#Four_kingdoms" title="Kingdom (biology)">4 kingdoms</a> </td> <td style="text-align: center; border-bottom: double black 3px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a href="/wiki/Kingdom_(biology)#Five_kingdoms" title="Kingdom (biology)">5 kingdoms</a> </td> <td style="text-align: center; border-bottom: double black 3px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a href="/wiki/Kingdom_(biology)#Six_kingdoms" title="Kingdom (biology)">6 kingdoms</a> </td> <td style="text-align: center; border-bottom: double black 3px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;">— </td> <td style="text-align: center; border-bottom: double black 3px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a href="/wiki/Kingdom_(biology)#Eight_kingdoms" title="Kingdom (biology)">8 kingdoms</a> </td> <td style="text-align: center; border-bottom: double black 3px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a href="/wiki/Kingdom_(biology)#Six_kingdoms_(1998)" title="Kingdom (biology)">6 kingdoms</a> </td> <td style="text-align: center; border-bottom: double black 3px; border-left: solid black 1px; padding-left: 4px; padding-right: 4px;"><a href="/wiki/Kingdom_(biology)#Seven_kingdoms" title="Kingdom (biology)">7 kingdoms</a> </td></tr> <tr> <td rowspan="5" style="text-align: center; padding-left: 4px;">— </td> <td rowspan="5" style="background-color:khaki; padding-left: 4px; padding-right: 4px; border-left: dotted black 1px;"><a href="/wiki/Protist" title="Protist">Protista</a> </td> <td rowspan="2" style="background-color:lightgrey; padding-left: 4px; padding-right: 4px; border-left: dotted black 1px;"><a href="/wiki/Prokaryota" class="mw-redirect" title="Prokaryota">Prokaryota</a> </td> <td rowspan="2" style="background-color:lightgrey; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Monera" title="Monera">Monera</a> </td> <td rowspan="2" style="background-color:lightgrey; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Monera" title="Monera">Monera</a> </td> <td style="background-color:lightgrey; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Eubacteria" class="mw-redirect" title="Eubacteria">Eubacteria</a> </td> <td style="background-color:lightgrey; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Bacteria" title="Bacteria">Bacteria</a> </td> <td style="background-color:lightgrey; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Eubacteria" class="mw-redirect" title="Eubacteria">Eubacteria</a> </td> <td rowspan="2" style="background-color:lightgrey; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Bacteria" title="Bacteria">Bacteria</a> </td> <td style="background-color:lightgrey; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Bacteria" title="Bacteria">Bacteria</a> </td></tr> <tr> <td style="background-color:darkgray; padding-left: 4px; padding-right: 4px; border-left: dotted black 1px;"><a href="/wiki/Archaebacteria" class="mw-redirect" title="Archaebacteria">Archaebacteria</a> </td> <td style="background-color:darkgray; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Archaea" title="Archaea">Archaea</a> </td> <td style="background-color:darkgray; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Archaebacteria" class="mw-redirect" title="Archaebacteria">Archaebacteria</a> </td> <td style="background-color:darkgray; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Archaea" title="Archaea">Archaea</a> </td></tr> <tr> <td rowspan="6" style="background-color:#e0d0b0; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Eukaryota" class="mw-redirect" title="Eukaryota">Eukaryota</a> </td> <td rowspan="3" style="background-color:khaki; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Protista" class="mw-redirect" title="Protista">Protista</a> </td> <td rowspan="3" style="background-color:khaki; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Protist" title="Protist">Protista</a> </td> <td rowspan="3" style="background-color:khaki; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Protist" title="Protist">Protista</a> </td> <td rowspan="6" style="background-color:#e0d0b0; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Eukaryote" title="Eukaryote">Eucarya</a> </td> <td rowspan="1" style="background-color:PeachPuff; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Archezoa" title="Archezoa">Archezoa</a> </td> <td rowspan="2" style="background-color:khaki; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Protozoa" title="Protozoa">Protozoa</a> </td> <td rowspan="2" style="background-color:khaki; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Protozoa" title="Protozoa">Protozoa</a> </td></tr> <tr> <td rowspan="1" style="background-color:khaki; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Protozoa" title="Protozoa">Protozoa</a> </td></tr> <tr> <td rowspan="1" style="background-color:burlywood; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Chromista" title="Chromista">Chromista</a> </td> <td rowspan="1" style="background-color:burlywood; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Chromista" title="Chromista">Chromista</a> </td> <td rowspan="1" style="background-color:burlywood; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Chromista" title="Chromista">Chromista</a> </td></tr> <tr> <td rowspan="2" style="background-color:lightgreen; padding-left: 4px;"><a href="/wiki/Vegetabilia" class="mw-redirect" title="Vegetabilia">Vegetabilia</a> </td> <td rowspan="2" style="background-color:lightgreen; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Plant" title="Plant">Plantae</a> </td> <td rowspan="2" style="background-color:lightgreen; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Plant" title="Plant">Plantae</a> </td> <td style="background-color:lightgreen; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Plant" title="Plant">Plantae</a> </td> <td style="background-color:lightgreen; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Plant" title="Plant">Plantae</a> </td> <td style="background-color:lightgreen; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Plant" title="Plant">Plantae</a> </td> <td style="background-color:lightgreen; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Plant" title="Plant">Plantae</a> </td> <td style="background-color:lightgreen; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Plant" title="Plant">Plantae</a> </td></tr> <tr> <td style="background-color:lightblue; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Fungus" title="Fungus">Fungi</a> </td> <td style="background-color:lightblue; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Fungus" title="Fungus">Fungi</a> </td> <td style="background-color:lightblue; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Fungus" title="Fungus">Fungi</a> </td> <td style="background-color:lightblue; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Fungus" title="Fungus">Fungi</a> </td> <td style="background-color:lightblue; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Fungus" title="Fungus">Fungi</a> </td></tr> <tr> <td style="background-color:pink; padding-left: 4px;"><a href="/wiki/Animal" title="Animal">Animalia</a> </td> <td style="background-color:pink; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Animal" title="Animal">Animalia</a> </td> <td style="background-color:pink; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Animal" title="Animal">Animalia</a> </td> <td style="background-color:pink; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Animal" title="Animal">Animalia</a> </td> <td style="background-color:pink; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Animal" title="Animal">Animalia</a> </td> <td style="background-color:pink; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Animal" title="Animal">Animalia</a> </td> <td style="background-color:pink; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Animal" title="Animal">Animalia</a> </td> <td style="background-color:pink; padding-left: 4px; border-left: dotted black 1px;"><a href="/wiki/Animal" title="Animal">Animalia</a> </td></tr></tbody></table> <p><br /> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Two-empire_system&action=edit&section=1" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Domain_(biology)" title="Domain (biology)">Domain (biology)</a></li> <li><a href="/wiki/Kingdom_(biology)" title="Kingdom (biology)">Kingdom (biology)</a></li> <li><a href="/wiki/Three-domain_system" title="Three-domain system">Three-domain system</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Two-empire_system&action=edit&section=2" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFCavalier-Smith2002" class="citation journal cs1">Cavalier-Smith, T (2002). <a rel="nofollow" class="external text" href="https://doi.org/10.1099%2F00207713-52-1-7">"The neomuran origin of archaebacteria, the negibacterial root of the universal tree and bacterial megaclassification"</a>. <i>International Journal of Systematic and Evolutionary Microbiology</i>. <b>52</b> (1): 7–76. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1099%2F00207713-52-1-7">10.1099/00207713-52-1-7</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/11837318">11837318</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=International+Journal+of+Systematic+and+Evolutionary+Microbiology&rft.atitle=The+neomuran+origin+of+archaebacteria%2C+the+negibacterial+root+of+the+universal+tree+and+bacterial+megaclassification&rft.volume=52&rft.issue=1&rft.pages=7-76&rft.date=2002&rft_id=info%3Adoi%2F10.1099%2F00207713-52-1-7&rft_id=info%3Apmid%2F11837318&rft.aulast=Cavalier-Smith&rft.aufirst=T&rft_id=https%3A%2F%2Fdoi.org%2F10.1099%252F00207713-52-1-7&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMayr1998" class="citation journal cs1">Mayr, E. (1998). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC33883">"Two empires or three?"</a>. <i>Proceedings of the National Academy of Sciences</i>. <b>95</b> (17): 9720–9723. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1998PNAS...95.9720M">1998PNAS...95.9720M</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1073%2Fpnas.95.17.9720">10.1073/pnas.95.17.9720</a></span>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC33883">33883</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/9707542">9707542</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Proceedings+of+the+National+Academy+of+Sciences&rft.atitle=Two+empires+or+three%3F&rft.volume=95&rft.issue=17&rft.pages=9720-9723&rft.date=1998&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC33883%23id-name%3DPMC&rft_id=info%3Apmid%2F9707542&rft_id=info%3Adoi%2F10.1073%2Fpnas.95.17.9720&rft_id=info%3Abibcode%2F1998PNAS...95.9720M&rft.aulast=Mayr&rft.aufirst=E.&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC33883&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGupta1998" class="citation journal cs1">Gupta, Radhey S (1998). "Life's Third Domain (Archaea): An Established Fact or an Endangered Paradigm?". <i>Theoretical Population Biology</i>. <b>54</b> (2): 91–104. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1006%2Ftpbi.1998.1376">10.1006/tpbi.1998.1376</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/9733652">9733652</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Theoretical+Population+Biology&rft.atitle=Life%27s+Third+Domain+%28Archaea%29%3A+An+Established+Fact+or+an+Endangered+Paradigm%3F&rft.volume=54&rft.issue=2&rft.pages=91-104&rft.date=1998&rft_id=info%3Adoi%2F10.1006%2Ftpbi.1998.1376&rft_id=info%3Apmid%2F9733652&rft.aulast=Gupta&rft.aufirst=Radhey+S&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-Linnaeus1735-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-Linnaeus1735_4-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLinnaeus1735" class="citation book cs1"><a href="/wiki/Carl_Linnaeus" title="Carl Linnaeus">Linnaeus, C.</a> (1735). <i>Systemae Naturae, sive regna tria naturae, systematics proposita per classes, ordines, genera & species</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Systemae+Naturae%2C+sive+regna+tria+naturae%2C+systematics+proposita+per+classes%2C+ordines%2C+genera+%26+species&rft.date=1735&rft.aulast=Linnaeus&rft.aufirst=C.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-Haeckel-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-Haeckel_5-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHaeckel1866" class="citation book cs1"><a href="/wiki/Ernst_Haeckel" title="Ernst Haeckel">Haeckel, E.</a> (1866). <i>Generelle Morphologie der Organismen</i>. Reimer, Berlin.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Generelle+Morphologie+der+Organismen&rft.pub=Reimer%2C+Berlin&rft.date=1866&rft.aulast=Haeckel&rft.aufirst=E.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-Chatton1925-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-Chatton1925_6-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFChatton1925" class="citation journal cs1 cs1-prop-long-vol"><a href="/wiki/%C3%89douard_Chatton" title="Édouard Chatton">Chatton, É.</a> (1925). <a rel="nofollow" class="external text" href="https://gallica.bnf.fr/ark:/12148/bpt6k55415433/f8">"<i>Pansporella perplexa</i>. Réflexions sur la biologie et la phylogénie des protozoaires"</a>. <i>Annales des Sciences Naturelles - Zoologie et Biologie Animale</i>. 10-VIII: 5–84.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Annales+des+Sciences+Naturelles+-+Zoologie+et+Biologie+Animale&rft.atitle=Pansporella+perplexa.+R%C3%A9flexions+sur+la+biologie+et+la+phylog%C3%A9nie+des+protozoaires&rft.volume=10-VIII&rft.pages=5-84&rft.date=1925&rft.aulast=Chatton&rft.aufirst=%C3%89.&rft_id=https%3A%2F%2Fgallica.bnf.fr%2Fark%3A%2F12148%2Fbpt6k55415433%2Ff8&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-Chatton-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-Chatton_7-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFChatton1937" class="citation book cs1"><a href="/wiki/%C3%89douard_Chatton" title="Édouard Chatton">Chatton, É.</a> (1937). <i>Titres et Travaux Scientifiques (1906–1937)</i>. E. Sottano, Sète, France.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Titres+et+Travaux+Scientifiques+%281906%E2%80%931937%29&rft.pub=E.+Sottano%2C+S%C3%A8te%2C+France&rft.date=1937&rft.aulast=Chatton&rft.aufirst=%C3%89.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-Copeland1938-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-Copeland1938_8-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCopeland1938" class="citation journal cs1"><a href="/wiki/Herbert_Copeland_(biologist)" title="Herbert Copeland (biologist)">Copeland, H.F.</a> (1938). "The kingdoms of organisms". <i>Quarterly Review of Biology</i>. <b>13</b> (4): 383–420. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1086%2F394568">10.1086/394568</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:84634277">84634277</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Quarterly+Review+of+Biology&rft.atitle=The+kingdoms+of+organisms&rft.volume=13&rft.issue=4&rft.pages=383-420&rft.date=1938&rft_id=info%3Adoi%2F10.1086%2F394568&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A84634277%23id-name%3DS2CID&rft.aulast=Copeland&rft.aufirst=H.F.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-Copeland1956-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-Copeland1956_9-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCopeland1956" class="citation book cs1"><a href="/wiki/Herbert_Copeland_(biologist)" title="Herbert Copeland (biologist)">Copeland, H.F.</a> (1956). <a rel="nofollow" class="external text" href="https://archive.org/stream/classificationof00cope#page/6/mode/2up"><i>The Classification of Lower Organisms</i></a>. Palo Alto: Pacific Books. p. 6. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.5962%2Fbhl.title.4474">10.5962/bhl.title.4474</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Classification+of+Lower+Organisms&rft.place=Palo+Alto&rft.pages=6&rft.pub=Pacific+Books&rft.date=1956&rft_id=info%3Adoi%2F10.5962%2Fbhl.title.4474&rft.aulast=Copeland&rft.aufirst=H.F.&rft_id=https%3A%2F%2Farchive.org%2Fstream%2Fclassificationof00cope%23page%2F6%2Fmode%2F2up&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-Whittaker1969-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-Whittaker1969_10-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWhittaker1969" class="citation journal cs1"><a href="/wiki/Robert_Whittaker_(ecologist)" title="Robert Whittaker (ecologist)">Whittaker, R.H.</a> (January 1969). "New concepts of kingdoms of organisms". <i>Science</i>. <b>163</b> (3863): 150–160. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1969Sci...163..150W">1969Sci...163..150W</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1126%2Fscience.163.3863.150">10.1126/science.163.3863.150</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/5762760">5762760</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Science&rft.atitle=New+concepts+of+kingdoms+of+organisms&rft.volume=163&rft.issue=3863&rft.pages=150-160&rft.date=1969-01&rft_id=info%3Apmid%2F5762760&rft_id=info%3Adoi%2F10.1126%2Fscience.163.3863.150&rft_id=info%3Abibcode%2F1969Sci...163..150W&rft.aulast=Whittaker&rft.aufirst=R.H.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-Woese1977-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-Woese1977_11-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWoeseBalchMagrumFox1977" class="citation journal cs1"><a href="/wiki/Carl_Woese" title="Carl Woese">Woese, C.R.</a>; Balch, W.E.; Magrum, L.J.; Fox, G.E.; Wolfe, R.S. (August 1977). "An ancient divergence among the bacteria". <i>Journal of Molecular Evolution</i>. <b>9</b> (4): 305–311. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1977JMolE...9..305B">1977JMolE...9..305B</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2FBF01796092">10.1007/BF01796092</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/408502">408502</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:27788891">27788891</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Molecular+Evolution&rft.atitle=An+ancient+divergence+among+the+bacteria&rft.volume=9&rft.issue=4&rft.pages=305-311&rft.date=1977-08&rft_id=info%3Adoi%2F10.1007%2FBF01796092&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A27788891%23id-name%3DS2CID&rft_id=info%3Apmid%2F408502&rft_id=info%3Abibcode%2F1977JMolE...9..305B&rft.aulast=Woese&rft.aufirst=C.R.&rft.au=Balch%2C+W.E.&rft.au=Magrum%2C+L.J.&rft.au=Fox%2C+G.E.&rft.au=Wolfe%2C+R.S.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-Woese1977b-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-Woese1977b_12-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWoeseFox1977" class="citation journal cs1"><a href="/wiki/Carl_Woese" title="Carl Woese">Woese, C.R.</a>; Fox, G.E. (November 1977). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC432104">"Phylogenetic structure of the prokaryotic domain: the primary kingdoms"</a>. <i>Proceedings of the National Academy of Sciences of the United States of America</i>. <b>74</b> (11): 5088–5090. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1977PNAS...74.5088W">1977PNAS...74.5088W</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1073%2Fpnas.74.11.5088">10.1073/pnas.74.11.5088</a></span>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC432104">432104</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/270744">270744</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America&rft.atitle=Phylogenetic+structure+of+the+prokaryotic+domain%3A+the+primary+kingdoms&rft.volume=74&rft.issue=11&rft.pages=5088-5090&rft.date=1977-11&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC432104%23id-name%3DPMC&rft_id=info%3Apmid%2F270744&rft_id=info%3Adoi%2F10.1073%2Fpnas.74.11.5088&rft_id=info%3Abibcode%2F1977PNAS...74.5088W&rft.aulast=Woese&rft.aufirst=C.R.&rft.au=Fox%2C+G.E.&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC432104&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-Woese1990-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-Woese1990_13-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWoeseKandlerWheelis1990" class="citation journal cs1"><a href="/wiki/Carl_Woese" title="Carl Woese">Woese, C.</a>; Kandler, O.; Wheelis, M. (1990). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC54159">"Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya"</a>. <i>Proceedings of the National Academy of Sciences of the United States of America</i>. <b>87</b> (12): 4576–4579. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1990PNAS...87.4576W">1990PNAS...87.4576W</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1073%2Fpnas.87.12.4576">10.1073/pnas.87.12.4576</a></span>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC54159">54159</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/2112744">2112744</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America&rft.atitle=Towards+a+natural+system+of+organisms%3A+proposal+for+the+domains+Archaea%2C+Bacteria%2C+and+Eucarya.&rft.volume=87&rft.issue=12&rft.pages=4576-4579&rft.date=1990&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC54159%23id-name%3DPMC&rft_id=info%3Apmid%2F2112744&rft_id=info%3Adoi%2F10.1073%2Fpnas.87.12.4576&rft_id=info%3Abibcode%2F1990PNAS...87.4576W&rft.aulast=Woese&rft.aufirst=C.&rft.au=Kandler%2C+O.&rft.au=Wheelis%2C+M.&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC54159&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCavalier-Smith1981" class="citation journal cs1"><a href="/wiki/Thomas_Cavalier-Smith" title="Thomas Cavalier-Smith">Cavalier-Smith, T.</a> (1981). "Eukaryote kingdoms: Seven or nine?". <i>Bio Systems</i>. <b>14</b> (3–4): 461–481. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2F0303-2647%2881%2990050-2">10.1016/0303-2647(81)90050-2</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/7337818">7337818</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Bio+Systems&rft.atitle=Eukaryote+kingdoms%3A+Seven+or+nine%3F&rft.volume=14&rft.issue=3%E2%80%934&rft.pages=461-481&rft.date=1981&rft_id=info%3Adoi%2F10.1016%2F0303-2647%2881%2990050-2&rft_id=info%3Apmid%2F7337818&rft.aulast=Cavalier-Smith&rft.aufirst=T.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCavalier-Smith1992" class="citation journal cs1"><a href="/wiki/Thomas_Cavalier-Smith" title="Thomas Cavalier-Smith">Cavalier-Smith, T.</a> (1992). "Origins of secondary metabolism". <i>Ciba Foundation Symposium</i>. Novartis Foundation Symposia. <b>171</b>: 64–80, discussion 80–7. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1002%2F9780470514344.ch5">10.1002/9780470514344.ch5</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780470514344" title="Special:BookSources/9780470514344"><bdi>9780470514344</bdi></a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/1302186">1302186</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Ciba+Foundation+Symposium&rft.atitle=Origins+of+secondary+metabolism&rft.volume=171&rft.pages=64-80%2C+discussion+80-7&rft.date=1992&rft_id=info%3Apmid%2F1302186&rft_id=info%3Adoi%2F10.1002%2F9780470514344.ch5&rft.isbn=9780470514344&rft.aulast=Cavalier-Smith&rft.aufirst=T.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCavalier-Smith1993" class="citation journal cs1">Cavalier-Smith, T. (1993). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC372943">"Kingdom protozoa and its 18 phyla"</a>. <i>Microbiological Reviews</i>. <b>57</b> (4): 953–994. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1128%2Fmmbr.57.4.953-994.1993">10.1128/mmbr.57.4.953-994.1993</a>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC372943">372943</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/8302218">8302218</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Microbiological+Reviews&rft.atitle=Kingdom+protozoa+and+its+18+phyla&rft.volume=57&rft.issue=4&rft.pages=953-994&rft.date=1993&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC372943%23id-name%3DPMC&rft_id=info%3Apmid%2F8302218&rft_id=info%3Adoi%2F10.1128%2Fmmbr.57.4.953-994.1993&rft.aulast=Cavalier-Smith&rft.aufirst=T.&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC372943&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCavalier-Smith1998" class="citation journal cs1"><a href="/wiki/Thomas_Cavalier-Smith" title="Thomas Cavalier-Smith">Cavalier-Smith, T.</a> (1998). <a rel="nofollow" class="external text" href="http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=685">"A revised six-kingdom system of life"</a>. <i>Biological Reviews</i>. <b>73</b> (3): 203–266. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1111%2Fj.1469-185X.1998.tb00030.x">10.1111/j.1469-185X.1998.tb00030.x</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/9809012">9809012</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:6557779">6557779</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Biological+Reviews&rft.atitle=A+revised+six-kingdom+system+of+life&rft.volume=73&rft.issue=3&rft.pages=203-266&rft.date=1998&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A6557779%23id-name%3DS2CID&rft_id=info%3Apmid%2F9809012&rft_id=info%3Adoi%2F10.1111%2Fj.1469-185X.1998.tb00030.x&rft.aulast=Cavalier-Smith&rft.aufirst=T.&rft_id=http%3A%2F%2Fjournals.cambridge.org%2Faction%2FdisplayAbstract%3FfromPage%3Donline%26aid%3D685&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-CavalierSmith2004-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-CavalierSmith2004_18-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCavalier-Smith2004" class="citation journal cs1"><a href="/wiki/Thomas_Cavalier-Smith" title="Thomas Cavalier-Smith">Cavalier-Smith, T.</a> (2004). <a rel="nofollow" class="external text" href="http://www.cladocera.de/protozoa/cavalier-smith_2004_prs.pdf">"Only six kingdoms of life"</a> <span class="cs1-format">(PDF)</span>. <i>Proceedings of the Royal Society B: Biological Sciences</i>. <b>271</b> (1545): 1251–1262. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1098%2Frspb.2004.2705">10.1098/rspb.2004.2705</a>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1691724">1691724</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/15306349">15306349</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2010-04-29</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Proceedings+of+the+Royal+Society+B%3A+Biological+Sciences&rft.atitle=Only+six+kingdoms+of+life&rft.volume=271&rft.issue=1545&rft.pages=1251-1262&rft.date=2004&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC1691724%23id-name%3DPMC&rft_id=info%3Apmid%2F15306349&rft_id=info%3Adoi%2F10.1098%2Frspb.2004.2705&rft.aulast=Cavalier-Smith&rft.aufirst=T.&rft_id=http%3A%2F%2Fwww.cladocera.de%2Fprotozoa%2Fcavalier-smith_2004_prs.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-pmid20031978-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-pmid20031978_19-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCavalier-Smith2010" class="citation journal cs1"><a href="/wiki/Thomas_Cavalier-Smith" title="Thomas Cavalier-Smith">Cavalier-Smith, T.</a> (June 2010). <a rel="nofollow" class="external text" href="http://rsbl.royalsocietypublishing.org/cgi/pmidlookup?view=long&pmid=20031978">"Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree"</a>. <i>Biol. Lett</i>. <b>6</b> (3): 342–345. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1098%2Frsbl.2009.0948">10.1098/rsbl.2009.0948</a>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2880060">2880060</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/20031978">20031978</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Biol.+Lett.&rft.atitle=Kingdoms+Protozoa+and+Chromista+and+the+eozoan+root+of+the+eukaryotic+tree&rft.volume=6&rft.issue=3&rft.pages=342-345&rft.date=2010-06&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC2880060%23id-name%3DPMC&rft_id=info%3Apmid%2F20031978&rft_id=info%3Adoi%2F10.1098%2Frsbl.2009.0948&rft.aulast=Cavalier-Smith&rft.aufirst=T.&rft_id=http%3A%2F%2Frsbl.royalsocietypublishing.org%2Fcgi%2Fpmidlookup%3Fview%3Dlong%26pmid%3D20031978&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> <li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRuggieroGordonOrrellBailly2015" class="citation journal cs1">Ruggiero, Michael A.; Gordon, Dennis P.; Orrell, Thomas M.; Bailly, Nicolas; Bourgoin, Thierry; Brusca, Richard C.; Cavalier-Smith, Thomas; Guiry, Michael D.; Kirk, Paul M.; Thuesen, Erik V. (2015). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4418965">"A higher level classification of all living organisms"</a>. <i>PLOS ONE</i>. <b>10</b> (4): e0119248. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2015PLoSO..1019248R">2015PLoSO..1019248R</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1371%2Fjournal.pone.0119248">10.1371/journal.pone.0119248</a></span>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4418965">4418965</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/25923521">25923521</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=PLOS+ONE&rft.atitle=A+higher+level+classification+of+all+living+organisms&rft.volume=10&rft.issue=4&rft.pages=e0119248&rft.date=2015&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4418965%23id-name%3DPMC&rft_id=info%3Apmid%2F25923521&rft_id=info%3Adoi%2F10.1371%2Fjournal.pone.0119248&rft_id=info%3Abibcode%2F2015PLoSO..1019248R&rft.aulast=Ruggiero&rft.aufirst=Michael+A.&rft.au=Gordon%2C+Dennis+P.&rft.au=Orrell%2C+Thomas+M.&rft.au=Bailly%2C+Nicolas&rft.au=Bourgoin%2C+Thierry&rft.au=Brusca%2C+Richard+C.&rft.au=Cavalier-Smith%2C+Thomas&rft.au=Guiry%2C+Michael+D.&rft.au=Kirk%2C+Paul+M.&rft.au=Thuesen%2C+Erik+V.&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4418965&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATwo-empire+system" class="Z3988"></span></span> </li> </ol></div></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Two-empire_system&oldid=1253240956">https://en.wikipedia.org/w/index.php?title=Two-empire_system&oldid=1253240956</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Category</a>: <ul><li><a href="/wiki/Category:High-level_systems_of_taxonomy" title="Category:High-level systems of taxonomy">High-level systems of taxonomy</a></li></ul></div><div id="mw-hidden-catlinks" class="mw-hidden-catlinks mw-hidden-cats-hidden">Hidden categories: <ul><li><a href="/wiki/Category:CS1:_long_volume_value" title="Category:CS1: long volume value">CS1: long volume value</a></li><li><a href="/wiki/Category:Articles_with_short_description" title="Category:Articles with short description">Articles with short description</a></li><li><a href="/wiki/Category:Short_description_is_different_from_Wikidata" title="Category:Short description is different from Wikidata">Short description is different from Wikidata</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last edited on 25 October 2024, at 00:52<span class="anonymous-show"> (UTC)</span>.</li> <li id="footer-info-copyright">Text is available under the <a href="/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License" title="Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License">Creative Commons Attribution-ShareAlike 4.0 License</a>; additional terms may apply. By using this site, you agree to the <a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Terms_of_Use" class="extiw" title="foundation:Special:MyLanguage/Policy:Terms of Use">Terms of Use</a> and <a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy" class="extiw" title="foundation:Special:MyLanguage/Policy:Privacy policy">Privacy Policy</a>. Wikipedia® is a registered trademark of the <a rel="nofollow" class="external text" href="https://wikimediafoundation.org/">Wikimedia Foundation, Inc.</a>, a non-profit organization.</li> </ul> <ul id="footer-places"> <li id="footer-places-privacy"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy">Privacy policy</a></li> <li id="footer-places-about"><a href="/wiki/Wikipedia:About">About Wikipedia</a></li> <li id="footer-places-disclaimers"><a href="/wiki/Wikipedia:General_disclaimer">Disclaimers</a></li> <li id="footer-places-contact"><a href="//en.wikipedia.org/wiki/Wikipedia:Contact_us">Contact Wikipedia</a></li> <li id="footer-places-wm-codeofconduct"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Universal_Code_of_Conduct">Code of Conduct</a></li> <li id="footer-places-developers"><a href="https://developer.wikimedia.org">Developers</a></li> <li id="footer-places-statslink"><a href="https://stats.wikimedia.org/#/en.wikipedia.org">Statistics</a></li> <li id="footer-places-cookiestatement"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Cookie_statement">Cookie statement</a></li> <li id="footer-places-mobileview"><a href="//en.m.wikipedia.org/w/index.php?title=Two-empire_system&mobileaction=toggle_view_mobile" class="noprint stopMobileRedirectToggle">Mobile view</a></li> </ul> <ul id="footer-icons" class="noprint"> <li id="footer-copyrightico"><a href="https://wikimediafoundation.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><img src="/static/images/footer/wikimedia-button.svg" width="84" height="29" alt="Wikimedia Foundation" loading="lazy"></a></li> <li id="footer-poweredbyico"><a href="https://www.mediawiki.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><img src="/w/resources/assets/poweredby_mediawiki.svg" alt="Powered by MediaWiki" width="88" height="31" loading="lazy"></a></li> </ul> </footer> </div> </div> </div> <div class="vector-settings" id="p-dock-bottom"> <ul></ul> </div><script>(RLQ=window.RLQ||[]).push(function(){mw.config.set({"wgHostname":"mw-web.codfw.main-694cf4987f-49njn","wgBackendResponseTime":178,"wgPageParseReport":{"limitreport":{"cputime":"0.333","walltime":"0.396","ppvisitednodes":{"value":1220,"limit":1000000},"postexpandincludesize":{"value":56866,"limit":2097152},"templateargumentsize":{"value":486,"limit":2097152},"expansiondepth":{"value":8,"limit":100},"expensivefunctioncount":{"value":1,"limit":500},"unstrip-depth":{"value":1,"limit":20},"unstrip-size":{"value":77684,"limit":5000000},"entityaccesscount":{"value":0,"limit":400},"timingprofile":["100.00% 337.179 1 -total"," 72.64% 244.926 1 Template:Reflist"," 55.24% 186.261 16 Template:Cite_journal"," 22.51% 75.913 1 Template:Short_description"," 13.05% 43.991 2 Template:Pagetype"," 6.02% 20.291 4 Template:Cite_book"," 5.21% 17.557 3 Template:Main_other"," 4.52% 15.243 1 Template:SDcat"," 3.99% 13.447 1 Template:Full_biological_kingdom_classification"," 0.65% 2.180 1 Template:Short_description/lowercasecheck"]},"scribunto":{"limitreport-timeusage":{"value":"0.200","limit":"10.000"},"limitreport-memusage":{"value":5177748,"limit":52428800}},"cachereport":{"origin":"mw-web.codfw.main-f69cdc8f6-l24nk","timestamp":"20241122155530","ttl":2592000,"transientcontent":false}}});});</script> <script type="application/ld+json">{"@context":"https:\/\/schema.org","@type":"Article","name":"Two-empire system","url":"https:\/\/en.wikipedia.org\/wiki\/Two-empire_system","sameAs":"http:\/\/www.wikidata.org\/entity\/Q3324187","mainEntity":"http:\/\/www.wikidata.org\/entity\/Q3324187","author":{"@type":"Organization","name":"Contributors to Wikimedia projects"},"publisher":{"@type":"Organization","name":"Wikimedia Foundation, Inc.","logo":{"@type":"ImageObject","url":"https:\/\/www.wikimedia.org\/static\/images\/wmf-hor-googpub.png"}},"datePublished":"2005-03-10T23:41:12Z","dateModified":"2024-10-25T00:52:51Z","image":"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/b\/ba\/Tree_of_Living_Organisms_2.png","headline":"taxonomic theory"}</script> </body> </html>