History of medicine - Germ Theory, Microbes, Vaccines

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This discovery changed the whole face of pathology and effected a complete revolution in the practice of surgery. The idea that disease was caused by entry into the body of imperceptible particles is of ancient date. 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border-right-sm border-left-sm open"> <div class="drawer d-flex flex-column open"> <div class="left-rail-section-content"> <div class="topic-left-rail-header text-truncate bg-gray-50 position-relative text-right d-flex align-items-center"> <div class="tlr-title px-20 py-15 text-left"> <em class="material-icons text-gray-400 d-lg-none" data-icon="toc"></em> <a class="font-serif font-weight-bold text-black link-blue" href="https://www.britannica.com/science/history-of-medicine">history of medicine</a> </div> <button aria-label="Close" class="js-sections-close-button btn-link btn-sm btn d-lg-none position-absolute top-0 p-10 right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <ul class="list-unstyled my-0" data-level="h1"><li data-target="#ref1"><div class="pl-25"><a class="link-gray-900 w-100" href="/science/history-of-medicine">Introduction</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref35641"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/history-of-medicine#ref35641">Medicine and surgery before 1800</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref35642"><a class="w-100 link-gray-900" href="/science/history-of-medicine#ref35642">Early medicine and folklore</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35643"><a class="w-100 link-gray-900" href="/science/history-of-medicine#ref35643">The ancient Middle East and Egypt</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35644"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Traditional-medicine-and-surgery-in-Asia">Traditional medicine and surgery in Asia</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref35645"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Traditional-medicine-and-surgery-in-Asia#ref35645">India</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35646"><a class="w-100 link-gray-900" href="/science/history-of-medicine/China">China</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35647"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Japan">Japan</a></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35648"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Japan#ref35648">The roots of Western medicine</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref35649"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Japan#ref35649">Early Greece</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35650"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Japan#ref35650">Hippocrates</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35651"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Hellenistic-and-Roman-medicine">Hellenistic and Roman medicine</a></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35652"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Hellenistic-and-Roman-medicine#ref35652">Christian and Muslim reservoirs of learning</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref35653"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Hellenistic-and-Roman-medicine#ref35653">Translators and saints</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35654"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Hellenistic-and-Roman-medicine#ref35654">Arabian medicine</a></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35655"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Hellenistic-and-Roman-medicine#ref35655">Medieval and Renaissance Europe</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref35656"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Hellenistic-and-Roman-medicine#ref35656">Salerno and the medical schools</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35657"><a class="w-100 link-gray-900" href="/science/history-of-medicine/The-spread-of-new-learning">The spread of new learning</a></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35658"><a class="w-100 link-gray-900" href="/science/history-of-medicine/The-spread-of-new-learning#ref35658">The Enlightenment</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref35659"><a class="w-100 link-gray-900" href="/science/history-of-medicine/The-spread-of-new-learning#ref35659">Harvey and the experimental method</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35660"><a class="w-100 link-gray-900" href="/science/history-of-medicine/The-spread-of-new-learning#ref35660">The futile search for an easy system</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35661"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-18th-century">Medicine in the 18th century</a></li></ul></li></ul></div></li><li data-target="#ref35662"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-18th-century#ref35662">The rise of scientific medicine in the 19th century</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref35663"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-18th-century#ref35663">Physiology</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35664"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Verification-of-the-germ-theory">Verification of the germ theory</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35665"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Verification-of-the-germ-theory#ref35665">Discoveries in clinical medicine and anesthesia</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35666"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Verification-of-the-germ-theory#ref35666">Advances at the end of the century</a></li></ul></div></li><li data-target="#ref35667"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-20th-century">Medicine in the 20th century</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref35668"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-20th-century#ref35668">Infectious diseases and chemotherapy</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref35669"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-20th-century#ref35669">Ehrlich and arsphenamine</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35670"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-20th-century#ref35670">Sulfonamide drugs</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35671" class="has-children"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-20th-century#ref35671">Antibiotics</a><ul class="list-unstyled" data-level="h4"><li data-target="#ref35672"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-20th-century#ref35672">Penicillin</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref35673"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-20th-century#ref35673">Antituberculous drugs</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref35674"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Medicine-in-the-20th-century#ref35674">Other antibiotics</a></li></ul></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35675"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Immunology">Immunology</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref35676" class="has-children"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Immunology#ref35676">Antibacterial vaccination</a><ul class="list-unstyled" data-level="h4"><li data-target="#ref35677"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Immunology#ref35677">Typhoid</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref35678"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Immunology#ref35678">Tetanus</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref35679"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Immunology#ref35679">Diphtheria</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref35680"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Immunology#ref35680">BCG vaccine for tuberculosis</a></li></ul></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35681"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Immunization-against-viral-diseases">Immunization against viral diseases</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35682"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Immunization-against-viral-diseases#ref35682">The immune response</a></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35683"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Immunization-against-viral-diseases#ref35683">Endocrinology</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref35684"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Insulin">Insulin</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35685"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Insulin#ref35685">Cortisone</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35686"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Insulin#ref35686">Sex hormones</a></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35687"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Insulin#ref35687">Vitamins</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35688"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Malignant-disease">Malignant disease</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35689"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Malignant-disease#ref35689">Tropical medicine</a></li></ul></div></li><li data-target="#ref35690"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/history-of-medicine/Malignant-disease#ref35690">Surgery in the 20th century</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref35691"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Malignant-disease#ref35691">The opening phase</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref35692"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Malignant-disease#ref35692">The situation encountered</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref35693" class="has-children"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Changes-before-World-War-I">Changes before World War I</a><ul class="list-unstyled" data-level="h4"><li data-target="#ref35694"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Changes-before-World-War-I#ref35694">Abdominal surgery</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref35695"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Changes-before-World-War-I#ref35695">Neurosurgery</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref35696"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Changes-before-World-War-I#ref35696">Radiology</a></li></ul></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref35697"><a class="w-100 link-gray-900" href="/science/history-of-medicine/Changes-before-World-War-I#ref35697">World War I</a></li></ul><ul 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Ashworth Underwood</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">Director, Wellcome Institute of the History of Medicine, London, 1946–64. Editor of <i>Science, Medicine and History.</i></div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> E. Ashworth Underwood</span>, <div class="editor-popover popover p-0"> <a class="d-block p-20 qa-editor-popup gtm-byline font-12 byline-contributor" href="/contributor/Philip-Rhodes/2449" > <div class="editor-title font-16 font-weight-bold">Philip Rhodes</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">Regional Postgraduate Dean of Medical Studies; Professor of Postgraduate Medical Education, University of Southampton, England, 1980–87. Author of <i>An Outline History of Medicine </i>and others.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> Philip Rhodes</span><span class="text-gray-700 mx-5">•</span><a class="see-all border-gray-700 gtm-byline" rel="nofollow" href="https://www.britannica.com/science/history-of-medicine/additional-info#contributors">All</a> </div> <div class="font-serif font-12 text-gray-700"> <span class="qa-fact-checked-by">Fact-checked by</span> <div class="editor-popover popover p-0"> <a class="d-block p-20 qa-editor-popup font-12" href="/editor/The-Editors-of-Encyclopaedia-Britannica/4419" > <div class="editor-title font-16 font-weight-bold">The Editors of Encyclopaedia Britannica</div> <div class="editor-description font-12 font-serif mt-5 text-black">Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2025-02-08T00:00:00CST" >Feb 8, 2025</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/science/history-of-medicine/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn border-2 ai-ask-button btn border-2 module-spacing btn-sm js-inline-ai-ask-button btn-outline-red-400 border-red-400 p-10 ml-5"> Ask the Chatbot a Question </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Key People: </dt> <dd><a href="/biography/Avicenna" topicid="45755">Avicenna</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Related Topics: </dt> <dd><a href="/science/medicine" topicid="372431">medicine</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>On the Web: </dt> <dd><a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(08)61293-3/fulltext" target="_blank">The Lancet - Medical historians and the history of medicine</a> (Feb. 08, 2025)</dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/history-of-medicine"> See all related content </a> </div> </div> </div> </div><span class="marker before-article"></span><section data-level="1"><span class="marker before-article"></span><section data-level="2" id="ref35664">  <span class="marker PREMOD1 mod-inline"></span><p class="topic-paragraph">Perhaps the overarching medical advance of the 19th century, certainly the most spectacular, was the conclusive demonstration that certain diseases, as well as the infection of surgical wounds, were directly caused by minute living organisms. This discovery changed the whole face of <a href="https://www.britannica.com/science/pathology" class="md-crosslink " data-show-preview="true">pathology</a> and effected a complete revolution in the practice of <a href="https://www.britannica.com/science/surgery-medicine" class="md-crosslink " data-show-preview="true">surgery</a>.</p><span class="marker MOD1 mod-inline"></span> <span class="marker PREMOD2 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="156999" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/14/137014-050-0E3A759B/hypothesis-generation-organisms-matter-Louis-Pasteur-experiments-1859.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/372460/156999"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/14/137014-050-0E3A759B/hypothesis-generation-organisms-matter-Louis-Pasteur-experiments-1859.jpg"><img src="https://cdn.britannica.com/14/137014-050-0E3A759B/hypothesis-generation-organisms-matter-Louis-Pasteur-experiments-1859.jpg?w=300" alt="experiments disproving spontaneous generation" data-width="1600" data-height="1334" loading="eager"></picture><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/14/137014-050-0E3A759B/hypothesis-generation-organisms-matter-Louis-Pasteur-experiments-1859.jpg" data-href="/media/1/372460/156999">experiments disproving spontaneous generation</a><span>The hypothesis of spontaneous generation posited that living organisms develop from nonliving matter. This idea was disproved following experiments conducted in 1668 by Italian physician Francesco Redi and in 1859 by French chemist and microbiologist Louis Pasteur.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div><p class="topic-paragraph">The idea that disease was caused by entry into the body of imperceptible particles is of ancient date. It was expressed by Roman encyclopaedist <span id="ref412830"></span><a href="https://www.britannica.com/biography/Marcus-Terentius-Varro" class="md-crosslink " data-show-preview="true">Marcus Terentius Varro</a> as early as 100 <span class="text-smallcaps">bce</span>, by <a href="https://www.britannica.com/biography/Girolamo-Fracastoro" class="md-crosslink " data-show-preview="true">Girolamo Fracastoro</a> in 1546, by <a href="https://www.britannica.com/biography/Athanasius-Kircher" class="md-crosslink " data-show-preview="true">Athanasius Kircher</a> and Pierre Borel about a century later, and by <span id="ref412831"></span><a href="https://www.britannica.com/biography/Francesco-Redi" class="md-crosslink " data-show-preview="true">Francesco Redi</a>, who in 1684 wrote his <em>Osservazioni intorno agli animali viventi che si trovano negli animali viventi</em> (“Observations on Living Animals Which Are to Be Found Within Other Living Animals”), in which he sought to disprove the idea of <a href="https://www.britannica.com/science/spontaneous-generation" class="md-crosslink " data-show-preview="true">spontaneous generation</a>. Everything must have a parent, he wrote; only life produces life. A 19th-century pioneer in this field, regarded by some as founder of the parasitic theory of infection, was <span id="ref412832"></span><a href="https://www.britannica.com/biography/Agostino-Bassi" class="md-crosslink " data-show-preview="true">Agostino Bassi</a> of Italy, who showed that a disease of silkworms was caused by a fungus that could be destroyed by chemical agents.</p><span class="marker MOD2 mod-inline"></span> <span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">The main <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="credit" href="https://www.britannica.com/dictionary/credit" data-type="EB">credit</a> for establishing the <a href="https://www.britannica.com/science/science" class="md-crosslink autoxref " data-show-preview="true">science</a> of <span id="ref412833"></span><a href="https://www.britannica.com/science/bacteriology" class="md-crosslink " data-show-preview="true">bacteriology</a> must be accorded to French chemist <span id="ref412834"></span><a href="https://www.britannica.com/biography/Louis-Pasteur" class="md-crosslink " data-show-preview="true">Louis Pasteur</a>. It was Pasteur who, by a brilliant series of experiments, proved that the <a href="https://www.britannica.com/science/fermentation" class="md-crosslink " data-show-preview="true">fermentation</a> of wine and the souring of milk are caused by living microorganisms. His work led to the <a href="https://www.britannica.com/technology/pasteurization" class="md-crosslink " data-show-preview="true">pasteurization</a> of milk and solved problems of agriculture and industry as well as those of animal and human diseases. He successfully employed inoculations to prevent <a href="https://www.britannica.com/science/anthrax-disease" class="md-crosslink " data-show-preview="true">anthrax</a> in sheep and cattle, chicken cholera in fowl, and finally <a href="https://www.britannica.com/science/rabies" class="md-crosslink " data-show-preview="true">rabies</a> in humans and dogs. The latter resulted in the widespread establishment of Pasteur institutes.</p><span class="marker MOD3 mod-inline"></span> <span class="marker PREMOD4 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="219696" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/78/186878-050-8C18826F/Joseph-Lister-1890.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/372460/219696"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/78/186878-050-8C18826F/Joseph-Lister-1890.jpg?w=300"><img src="https://cdn.britannica.com/78/186878-050-8C18826F/Joseph-Lister-1890.jpg?w=300" alt="Joseph Lister" data-width="1200" data-height="1600" loading="eager"></picture><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/78/186878-050-8C18826F/Joseph-Lister-1890.jpg" data-href="/media/1/372460/219696">Joseph Lister</a><span>Joseph Lister, c. 1890.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div><p class="topic-paragraph">From Pasteur, <span id="ref412836"></span><a href="https://www.britannica.com/biography/Joseph-Lister-Baron-Lister-of-Lyme-Regis" class="md-crosslink " data-show-preview="true">Joseph Lister</a> derived the concepts that enabled him to introduce the <span id="ref412837"></span><a href="https://www.britannica.com/science/antiseptic" class="md-crosslink " data-show-preview="true">antiseptic</a> principle into surgery. In 1865 Lister, a professor of surgery at Glasgow University, began placing an antiseptic barrier of <a href="https://www.britannica.com/science/carbolic-acid" class="md-crosslink " data-show-preview="true">carbolic acid</a> between the wound and the germ-containing atmosphere. <span id="ref412838"></span><a href="https://www.britannica.com/science/infection" class="md-crosslink ">Infections</a> and deaths fell dramatically, and his pioneering work led to more refined techniques of sterilizing the surgical <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="environment" href="https://www.merriam-webster.com/dictionary/environment" data-type="MW">environment</a>.</p><span class="marker MOD4 mod-inline"></span> <span class="marker PREMOD5 mod-inline"></span><p class="topic-paragraph">Advances in obstetrics had already been made by individuals such as Alexander Gordon at Aberdeen, Scotland, <span id="ref412839"></span><a href="https://www.britannica.com/biography/Oliver-Wendell-Holmes" class="md-crosslink " data-show-preview="true">Oliver Wendell Holmes</a> at Boston, and <span id="ref412840"></span><a href="https://www.britannica.com/biography/Ignaz-Semmelweis" class="md-crosslink " data-show-preview="true">Ignaz Semmelweis</a> at <a href="https://www.britannica.com/place/Vienna" class="md-crosslink " data-show-preview="true">Vienna</a> and Pest (<a href="https://www.britannica.com/place/Budapest" class="md-crosslink " data-show-preview="true">Budapest</a>), who advocated disinfection of the hands and clothing of <a href="https://www.britannica.com/science/midwifery" class="md-crosslink " data-show-preview="true">midwives</a> and medical students who attended confinements. These measures produced a marked reduction in cases of <a href="https://www.britannica.com/science/puerperal-fever" class="md-crosslink " data-show-preview="true">puerperal fever</a>, the <span id="ref412835"></span><a href="https://www.britannica.com/science/bacteria" class="md-crosslink " data-show-preview="true">bacterial</a> scourge of women following childbirth.</p><div class="module-spacing"> </div><span class="marker MOD5 mod-inline"></span> <span class="marker PREMOD6 mod-inline"></span><p class="topic-paragraph">Another pioneer in <a href="https://www.britannica.com/science/bacteriology" class="md-crosslink " data-show-preview="true">bacteriology</a> was German physician <span id="ref412841"></span><a href="https://www.britannica.com/biography/Robert-Koch" class="md-crosslink " data-show-preview="true">Robert Koch</a>, who showed how bacteria could be <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="cultivated" href="https://www.merriam-webster.com/dictionary/cultivated" data-type="MW">cultivated</a>, isolated, and examined in the laboratory. A <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="meticulous" href="https://www.merriam-webster.com/dictionary/meticulous" data-type="MW">meticulous</a> investigator, Koch discovered the organisms of <a href="https://www.britannica.com/science/tuberculosis" class="md-crosslink " data-show-preview="true">tuberculosis</a> in 1882 and of <a href="https://www.britannica.com/science/cholera" class="md-crosslink " data-show-preview="true">cholera</a> in 1883. By the end of the century many other disease-producing microorganisms had been identified.</p><span class="marker MOD6 mod-inline"></span> </section> <section data-level="2" id="ref35665"> <h2 class="h2">Discoveries in clinical medicine and anesthesia</h2> <span class="marker PREMOD7 mod-inline"></span><p class="topic-paragraph">There was perhaps some danger that in the search for bacteria other causes of disease would escape detection. Many physicians, however, were working along different lines in the 19th century. Among them were a group attached to Guy’s Hospital in <a href="https://www.britannica.com/place/London" class="md-crosslink " data-show-preview="true">London</a>: <a href="https://www.britannica.com/biography/Richard-Bright" class="md-crosslink " data-show-preview="true">Richard Bright</a>, <a href="https://www.britannica.com/biography/Thomas-Addison" class="md-crosslink " data-show-preview="true">Thomas Addison</a>, and <a href="https://www.britannica.com/biography/Sir-William-Withey-Gull-1st-Baronet" class="md-crosslink " data-show-preview="true">Sir William Gull</a>. Bright contributed significantly to the knowledge of kidney diseases, including <a href="https://www.britannica.com/science/Bright-disease" class="md-crosslink " data-show-preview="true">Bright disease</a>, and Addison gave his name to disorders of the <a href="https://www.britannica.com/science/adrenal-gland" class="md-crosslink " data-show-preview="true">adrenal glands</a> and the <a href="https://www.britannica.com/science/blood-biochemistry" class="md-crosslink " data-show-preview="true">blood</a>. Gull, a famous clinical teacher, left a <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="legacy" href="https://www.merriam-webster.com/dictionary/legacy" data-type="MW">legacy</a> of pithy <a href="https://www.britannica.com/art/aphorism" class="md-crosslink " data-show-preview="true">aphorisms</a> that might well rank with those of Hippocrates.</p><span class="marker MOD7 mod-inline"></span> <span class="marker PREMOD8 mod-inline"></span><p class="topic-paragraph">In <a href="https://www.britannica.com/place/Dublin" class="md-crosslink " data-show-preview="true">Dublin</a> <a href="https://www.britannica.com/biography/Robert-Graves" class="md-crosslink " data-show-preview="true">Robert Graves</a> and <a href="https://www.britannica.com/biography/William-Stokes" class="md-crosslink " data-show-preview="true">William Stokes</a> introduced new methods in clinical <a href="https://www.britannica.com/science/diagnosis" class="md-crosslink autoxref " data-show-preview="true">diagnosis</a> and medical training, while in <a href="https://www.britannica.com/place/Paris" class="md-crosslink " data-show-preview="true">Paris</a> a leading clinician, Pierre-Charles-Alexandre Louis, was attracting many students from America by the excellence of his teaching. By the early 19th century the <a href="https://www.britannica.com/place/United-States" class="md-crosslink " data-show-preview="true">United States</a> was ready to send back the results of its own researches and breakthroughs. In 1809, in a small Kentucky town, <a href="https://www.britannica.com/biography/Ephraim-McDowell" class="md-crosslink " data-show-preview="true">Ephraim McDowell</a> boldly operated on a woman—without <a href="https://www.britannica.com/science/anesthesia" class="md-crosslink " data-show-preview="true">anesthesia</a> or antisepsis—and successfully removed a large ovarian tumour. <span id="ref412842"></span><a href="https://www.britannica.com/biography/William-Beaumont" class="md-crosslink " data-show-preview="true">William Beaumont</a>, in treating a shotgun wound of the <a href="https://www.britannica.com/science/stomach" class="md-crosslink " data-show-preview="true">stomach</a>, was led to make many original observations that were published in 1833 as <em>Experiments and Observations on the Gastric Juice and the Physiology of Digestion</em>.</p><span class="marker MOD8 mod-inline"></span> <span class="marker PREMOD9 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="160518" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/25/131925-050-87501C61/ether-anesthesia-demonstration-William-Thomas-Green-Morton.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/372460/160518"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/25/131925-050-87501C61/ether-anesthesia-demonstration-William-Thomas-Green-Morton.jpg?w=300"><img src="https://cdn.britannica.com/25/131925-050-87501C61/ether-anesthesia-demonstration-William-Thomas-Green-Morton.jpg?w=300" alt="William Thomas Green Morton administering ether anesthesia" data-width="1600" data-height="1303" loading="eager"></picture><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/25/131925-050-87501C61/ether-anesthesia-demonstration-William-Thomas-Green-Morton.jpg" data-href="/media/1/372460/160518">William Thomas Green Morton administering ether anesthesia</a><span>William Thomas Green Morton administering ether anesthesia during the first successful public demonstration of its use during surgery, undated engraving.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div><p class="topic-paragraph">The most famous contribution by the United States to medical progress at this period was undoubtedly the introduction of general <span id="ref412843"></span><a href="https://www.britannica.com/science/anesthesia" class="md-crosslink " data-show-preview="true">anesthesia</a>, a procedure that not only liberated the patient from the fearful pain of surgery but also enabled the surgeon to perform more extensive operations. The discovery was marred by controversy. <a href="https://www.britannica.com/biography/Crawford-Williamson-Long" class="md-crosslink " data-show-preview="true">Crawford Long</a>, <a href="https://www.britannica.com/biography/Gardner-Quincy-Colton" class="md-crosslink " data-show-preview="true">Gardner Colton</a>, <a href="https://www.britannica.com/biography/Horace-Wells" class="md-crosslink " data-show-preview="true">Horace Wells</a>, and <a href="https://www.britannica.com/biography/Charles-Thomas-Jackson" class="md-crosslink " data-show-preview="true">Charles Jackson</a> are all claimants for priority; some used <span id="ref412844"></span><a href="https://www.britannica.com/science/nitrous-oxide" class="md-crosslink " data-show-preview="true">nitrous oxide</a> <a href="https://www.britannica.com/science/gas-state-of-matter" class="md-crosslink " data-show-preview="true">gas</a>, and others employed <span id="ref412845"></span><a href="https://www.britannica.com/science/ether-chemical-compound" class="md-crosslink " data-show-preview="true">ether</a>, which was less <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="capricious" href="https://www.merriam-webster.com/dictionary/capricious" data-type="MW">capricious</a>. There is little doubt, however, that it was <span id="ref412846"></span><a href="https://www.britannica.com/biography/William-Thomas-Green-Morton" class="md-crosslink " data-show-preview="true">William Thomas Green Morton</a> who, on October 16, 1846, at Massachusetts General Hospital in Boston, first demonstrated before a gathering of physicians the use of <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="ether" href="https://www.merriam-webster.com/dictionary/ether" data-type="MW">ether</a> as a general anesthetic. The news quickly reached Europe, and general anesthesia soon became prevalent in surgery. At Edinburgh, the professor of midwifery, <span id="ref412847"></span><a href="https://www.britannica.com/biography/Sir-James-Young-Simpson-1st-Baronet" class="md-crosslink " data-show-preview="true">James Young Simpson</a>, had been experimenting upon himself and his assistants, inhaling various vapours with the object of discovering an effective anesthetic. In November 1847 <span id="ref412848"></span><a href="https://www.britannica.com/science/chloroform" class="md-crosslink " data-show-preview="true">chloroform</a> was tried with complete success, and soon it was preferred to ether and became the anesthetic of choice.</p><span class="marker MOD9 mod-inline"></span> </section> <section data-level="2" id="ref35666"> <h2 class="h2">Advances at the end of the century</h2> <span class="marker PREMOD10 mod-inline"></span><p class="topic-paragraph">While antisepsis and anesthesia placed surgery on an entirely new footing, similarly important work was carried out in other fields of study, such as <a href="https://www.britannica.com/science/parasitology" class="md-crosslink " data-show-preview="true">parasitology</a> and disease <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="transmission" href="https://www.britannica.com/dictionary/transmission" data-type="EB">transmission</a>. <span id="ref412849"></span><a href="https://www.britannica.com/biography/Patrick-Manson" class="md-crosslink " data-show-preview="true">Patrick Manson</a>, a British pioneer in <a href="https://www.britannica.com/science/tropical-medicine" class="md-crosslink autoxref " data-show-preview="true">tropical medicine</a>, showed in China in 1877 how insects can carry disease and how the <a href="https://www.britannica.com/science/embryo-human-and-animal" class="md-crosslink " data-show-preview="true">embryos</a> of the <span id="ref412850"></span><a href="https://www.britannica.com/animal/filarial-worm" class="md-crosslink " data-show-preview="true"><em>Filaria</em></a> worm, which can cause <a href="https://www.britannica.com/science/elephantiasis" class="md-crosslink " data-show-preview="true">elephantiasis</a>, are transmitted by the <a href="https://www.britannica.com/technology/Mosquito-British-aircraft" class="md-crosslink " data-show-preview="true">mosquito</a>. Manson explained his views to <a href="https://www.britannica.com/topic/British-Army" class="md-crosslink autoxref " data-show-preview="true">British army</a> surgeon <span id="ref412851"></span><a href="https://www.britannica.com/biography/Ronald-Ross" class="md-crosslink " data-show-preview="true">Ronald Ross</a>, who was then working on the problem of <span id="ref412852"></span><a href="https://www.britannica.com/science/malaria" class="md-crosslink " data-show-preview="true">malaria</a>. Ross discovered the malarial parasite in the stomach of the <em>Anopheles</em> mosquito in 1897.</p><span class="marker MOD10 mod-inline"></span> <span class="marker PREMOD11 mod-inline"></span><p class="topic-paragraph">In Cuba, <span id="ref412853"></span><a href="https://www.britannica.com/biography/Carlos-J-Finlay" class="md-crosslink " data-show-preview="true">Carlos Finlay</a> expressed the view in 1881 that <span id="ref412854"></span><a href="https://www.britannica.com/science/yellow-fever" class="md-crosslink " data-show-preview="true">yellow fever</a> is carried by the <em>Stegomyia fasciata</em> (later renamed <em>Aedes aegypti</em>) mosquito. Following his lead, American researchers <a href="https://www.britannica.com/biography/Walter-Reed" class="md-crosslink " data-show-preview="true">Walter Reed</a>, <a href="https://www.britannica.com/biography/William-Crawford-Gorgas" class="md-crosslink " data-show-preview="true">William Gorgas</a>, and others were able to conquer the scourge of yellow fever in Panama and made possible the completion of the <span id="ref412855"></span><a href="https://www.britannica.com/topic/Panama-Canal" class="md-crosslink " data-show-preview="true">Panama Canal</a> by reducing the <a href="https://www.britannica.com/science/mortality-demography" class="md-crosslink autoxref " data-show-preview="true">death rate</a> there from 176 per 1,000 to 6 per 1,000.</p><span class="marker MOD11 mod-inline"></span> <span class="marker PREMOD12 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="13864" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/64/20964-004-80386569/Wilhelm-Conrad-Rontgen.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/372460/13864"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/64/20964-004-80386569/Wilhelm-Conrad-Rontgen.jpg?w=300"><img src="https://cdn.britannica.com/64/20964-004-80386569/Wilhelm-Conrad-Rontgen.jpg?w=300" alt="Wilhelm Conrad Röntgen" data-width="315" data-height="450" loading="eager"></picture><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/64/20964-004-80386569/Wilhelm-Conrad-Rontgen.jpg" data-href="/media/1/372460/13864">Wilhelm Conrad Röntgen</a><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div><p class="topic-paragraph">Other victories in <a href="https://www.britannica.com/science/preventive-medicine" class="md-crosslink " data-show-preview="true">preventive medicine</a> ensued, because the maintenance of health was now becoming as important a concern as the cure of disease, and the 20th century was to witness the evolution and progress of national health services in a number of countries. In addition, spectacular advances in <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="diagnosis" href="https://www.merriam-webster.com/dictionary/diagnosis" data-type="MW">diagnosis</a> and <a href="https://www.britannica.com/science/therapeutics" class="md-crosslink autoxref " data-show-preview="true">treatment</a> followed the discovery of <a href="https://www.britannica.com/science/X-ray" class="md-crosslink " data-show-preview="true">X-rays</a> by <a href="https://www.britannica.com/biography/Wilhelm-Rontgen" class="md-crosslink " data-show-preview="true">Wilhelm Conrad Röntgen</a>, in 1895, and of radium by <a href="https://www.britannica.com/biography/Pierre-Curie" class="md-crosslink " data-show-preview="true">Pierre</a> and <a href="https://www.britannica.com/biography/Marie-Curie" class="md-crosslink " data-show-preview="true">Marie Curie</a>, in 1898. Before the turn of the century, too, the vast new field of <a href="https://www.britannica.com/science/psychiatry" class="md-crosslink autoxref " data-show-preview="true">psychiatry</a> had been opened up by <a href="https://www.britannica.com/biography/Sigmund-Freud" class="md-crosslink " data-show-preview="true">Sigmund Freud</a>. The tremendous increase in scientific knowledge during the 19th century radically altered and expanded the practice of <a href="https://www.britannica.com/science/medicine" class="md-crosslink autoxref " data-show-preview="true">medicine</a>. Concern for upholding the quality of services led to the establishment of public and professional bodies to govern the standards for medical training and practice.</p><span class="marker MOD12 mod-inline"></span> <span class="md-signature"><a href="/contributor/Douglas-James-Guthrie/1186">Douglas James Guthrie</a></span> <span class="md-signature"><a href="/contributor/Philip-Rhodes/2449">Philip Rhodes</a></span> </section> </section> <span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article> </div> </div> </div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script type="text/javascript" id="_informizely_script_tag"> var IzWidget = IzWidget || {}; (function (d) { var scriptElement = d.createElement('script'); scriptElement.type = 'text/javascript'; scriptElement.async = true; scriptElement.src = "https://insitez.blob.core.windows.net/site/f780f33e-a610-4ac2-af81-3eb184037547.js"; var node = d.getElementById('_informizely_script_tag'); node.parentNode.insertBefore(scriptElement, node); } )(document); </script>  <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":8,"pagesTotal":17,"pageId":372460,"pageLength":1201,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-133/js/libs/jquery-3.5.0.min.js?v=3.133.9"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-133/dist/topic-page.js?v=3.133.9' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"D","adLeg":"C","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"PAGINATED","gisted":false,"pageNumber":8,"hasSummarizeButton":false,"hasAskButton":true} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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