Rudolf Virchow

Illustration of Virchow's cell theory

Virchow is credited with several key discoveries. His most widely known scientific contribution is his cell theory, which built on the work of Theodor Schwann. He was one of the first to accept the work of Robert Remak, who showed that the origin of cells was the division of pre-existing cells.[27] He did not initially accept the evidence for cell division and believed that it occurs only in certain types of cells. When it dawned on him that Remak might be right in 1855, he published Remak's work as his own, which caused a falling-out between the two.[28] Virchow was particularly influenced in cellular theory by the work of John Goodsir of Edinburgh, whom he described, as "one of the earliest and most acute observers of cell-life both physiological and pathological". Virchow dedicated his magnum opus Die Cellularpathologie to Goodsir.[29] Virchow's cellular theory was encapsulated in the epigram Omnis cellula e cellula ("all cells (come) from cells"), which he published in 1855.[8][20][30] (The epigram was actually coined by François-Vincent Raspail, but popularized by Virchow.)[31] It is a rejection of the concept of spontaneous generation, which held that organisms could arise from nonliving matter. For example, maggots were believed to appear spontaneously in decaying meat; Francesco Redi carried out experiments that disproved this notion and coined the maxim Omne vivum ex ovo ("Every living thing comes from a living thing" — literally "from an egg"); Virchow (and his predecessors) extended this to state that the only source for a living cell was another living cell.[32]

In 1845, Virchow and John Hughes Bennett independently observed abnormal increases in white blood cells in some patients. Virchow correctly identified the condition as a blood disease, and named it leukämie in 1847 (later anglicised to leukemia).[33][34][35] In 1857, he was the first to describe a type of tumour called chordoma that originated from the clivus (at the base of the skull).[36][37]

Virchow was the first to correctly link the origin of cancers from otherwise normal cells.[38] (His teacher Müller had proposed that cancers originated from cells, but from special cells, which he called blastema.) In 1855, he suggested that cancers arise from the activation of dormant cells (perhaps similar to cells now known as stem cells) present in mature tissue.[39] Virchow believed that cancer is caused by severe irritation in the tissues, and his theory came to be known as chronic irritation theory. He thought, rather wrongly, that the irritation spread in the form of liquid so that cancer rapidly increases.[40] His theory was largely ignored, as he was proved wrong that it was not by liquid, but by metastasis of the already cancerous cells that cancers spread. (Metastatis was first described by Karl Thiersch in the 1860s.)[41] But he made a crucial observation that certain cancers (carcinoma in the modern sense) were inherently associated with white blood cells (which are now called macrophages) that produced irritation (inflammation). It was only towards the end of the 20th century that Virchow's theory was taken seriously.[42] It was realised that specific cancers (including those of mesothelioma, lung, prostate, bladder, pancreatic, cervical, esophageal, melanoma, and head and neck) are indeed strongly associated with long-term inflammation.[43][44] In addition it became clear that prolonged use of anti-inflammatory drugs, such as aspirin, reduced cancer risk.[45] Experiments also show that drugs that block inflammation simultaneously inhibit tumour formation and development.[46]

Virchow was one of the leading physicians to Kaiser Frederick III, who suffered from cancer of the larynx. While other physicians such as Ernst von Bergmann suggested surgical removal of the entire larynx, Virchow was opposed to it because no successful operation of this kind had ever been done. The British surgeon Morell Mackenzie, performed a biopsy of the Kaiser in 1887 and sent it to Virchow, who identified it as "pachydermia verrucosa laryngis". Virchow affirmed that the tissues were not cancerous, even after several biopsy tests. The Kaiser died on 15 June 1888. The next day a post-mortem examination was performed by Virchow and his assistant. They found that the larynx was extensively damaged by ulceration, and microscopic examination confirmed epidermal carcinoma. Die Krankheit Kaiser Friedrich des Dritten (The Medical Report of Kaiser Frederick III) was published on 11 July under the lead authorship of Bergmann. But Virchow and Mackenzie were omitted, and they were particularly criticised for all their works.[47] The arguments between them turned into a century-long controversy, resulting in Virchow being accused of misdiagnosis and malpractice. But reassessment of the diagnostic history revealed that Virchow was right in his findings and decisions. It is now believed that the Kaiser had hybrid verrucous carcinoma, a very rare form of verrucous carcinoma, and that Virchow had no way of correctly identifying it.[48][49][50] (The cancer type was correctly identified only in 1948 by Lauren Ackerman.)[51][52]

Another significant credit relates to the discovery, made approximately simultaneously by Virchow and Charles Emile Troisier, that an enlarged left supraclavicular node is one of the earliest signs of gastrointestinal malignancy, commonly of the stomach, or less commonly, lung cancer. This has become known as Virchow's node and simultaneously Troisier's sign.[53][54]

Virchow is also known for elucidating the mechanism of pulmonary thromboembolism (a condition of blood clotting in the blood vessels), coining the terms embolism and thrombosis.[55] He noted that blood clots in the pulmonary artery originate first from venous thrombi, stating in 1859:

[T]he detachment of larger or smaller fragments from the end of the softening thrombus which are carried along by the current of blood and driven into remote vessels. This gives rise to the very frequent process on which I have bestowed the name of Embolia."[56]

Having made these initial discoveries based on autopsies, he proceeded to put forward a scientific hypothesis; that pulmonary thrombi are transported from the veins of the leg and that the blood has the ability to carry such an object. He then proceeded to prove this hypothesis by well-designed experiments, repeated numerous times to consolidate evidence, and with meticulously detailed methodology. This work rebutted a claim made by the eminent French pathologist Jean Cruveilhier that phlebitis led to clot development and that thus coagulation was the main consequence of venous inflammation. This was a view held by many before Virchow's work. Related to this research, Virchow described the factors contributing to venous thrombosis, Virchow's triad.[20][57]

Virchow founded the medical fields of cellular pathology and comparative pathology (comparison of diseases common to humans and animals). His most important work in the field was Cellular Pathology (Die Cellularpathologie in ihrer Begründung auf physiologische und pathologische Gewebelehre) published in 1858, as a collection of his lectures.[25] This is regarded as the basis of modern medical science,[58] and the "greatest advance which scientific medicine had made since its beginning."[59] His very innovative work may be viewed as between that of Giovanni Battista Morgagni, whose work Virchow studied, and that of Paul Ehrlich, who studied at the Charité while Virchow was developing microscopic pathology there. One of Virchow's major contributions to German medical education was to encourage the use of microscopes by medical students, and he was known for constantly urging his students to "think microscopically". He was the first to establish a link between infectious diseases between humans and animals, for which he coined the term "zoonoses".[60] He also introduced scientific terms such as "chromatin", "agenesis", "parenchyma", "osteoid", "amyloid degeneration", and "spina bifida".[61] His concepts on pathology directly opposed humourism, an ancient medical dogma that diseases were due to imbalanced body fluids, hypothetically called humours, that still pervaded.[62]

Virchow worked out the life cycle of a roundworm Trichinella spiralis. Virchow noticed a mass of circular white flecks in the muscle of dog and human cadavers, similar to those described by Richard Owen in 1835. He confirmed by microscopic observation that the white particles were indeed the larvae of roundworms, curled up in the muscle tissue. Rudolph Leukart found that these tiny worms could develop into adult roundworms in the intestine of a dog. He correctly asserted that these worms could also cause human helminthiasis. Virchow further demonstrated that if the infected meat is first heated to 137 °F for 10 minutes, the worms could not infect dogs or humans.[63] He established that human roundworm infection occurs via contaminated pork. This directly led to the establishment of meat inspection, which was first adopted in Berlin.[64][65]

Virchow was the first to develop a systematic method of autopsy, based on his knowledge of cellular pathology. The modern autopsy still constitutes his techniques.[66] His first significant autopsy was on a 50-year-old woman in 1845. He found an unusual number of white blood cells, and gave a detailed description in 1847 and named the condition as leukämie.[67] One on his autopsies in 1857 was the first description of vertebral disc rupture.[18][68] His autopsy on a baby in 1856 was the first description of congenital pulmonary lymphangiectasia (the name given by K. M. Laurence a century later), a rare and fatal disease of the lung.[69] From his experience of post-mortem examinations of a number of cadavers, he published his method in a small book in 1876.[70] His book was the first to describe the techniques of autopsy specifically to examine abnormalities in organs, and retain important tissues for further examination and demonstration. Unlike any other earlier practitioner, he practiced complete surgery of all body parts with body organs dissected one by one. This has become the standard method.[71][72]

Virchow discovered the clinical syndrome which he called ochronosis, a metabolic disorder in which a patient accumulates homogentisic acid in connective tissues and which can be identified by discolouration seen under the microscope. He found the unusual symptom in an autopsy of the corpse of a 67-year-old man on 8 May 1884. This was the first time this abnormal disease affecting cartilage and connective tissue was observed and characterised. His description and coining of the name appeared in the October 1866 issue of Vichows Archiv.[73][74][75]

Virchow was the first to analyse hair in criminal investigation, and made the first forensic report on it in 1861.[76] He was called as an expert witness in a murder case, and he used hair samples collected from the victim. He became the first to recognise the limitation of hair as evidence. He found that hairs can be different in an individual, that individual hair has characteristic features, and that hairs from different individuals can be strikingly similar. He concluded that evidence based on hair analysis is inconclusive.[77] His testimony runs:

[T]he hairs found on the defendant do not possess any so pronounced peculiarities or individualities [so] that no one with certainty has the right to assert that they must have originated from the head of the victim.[12]

Portrait of Rudolf Virchow by Hugo Vogel, 1861

Virchow developed an interest in anthropology in 1865, when he discovered pile dwellings in northern Germany. In 1869, he co-founded the German Anthropological Association. In 1870 he founded the Berlin Society for Anthropology, Ethnology, and Prehistory (Berliner Gesellschaft für Anthropologie, Ethnologie und Urgeschichte) which was very influential in coordinating and intensifying German archaeological research. Until his death, Virchow was several times (at least fifteen times) its president, often taking turns with his former student Adolf Bastian.[7] As president, Virchow frequently contributed to and co-edited the society's main journal Zeitschrift für Ethnologie (Journal of Ethnology), which Adolf Bastian, together with another student of Virchow, Robert Hartman, had founded in 1869.[78][79] In 1870, he led a major excavation of the hill forts in Pomerania. He also excavated wall mounds in Wöllstein in 1875 with Robert Koch, whose paper he edited on the subject.[16] For his contributions in German archaeology, the Rudolf Virchow lecture is held annually in his honour. He made field trips to Asia Minor, the Caucasus, Egypt, Nubia, and other places, sometimes in the company of Heinrich Schliemann. His 1879 journey to the site of Troy is described in Beiträge zur Landeskunde in Troas ("Contributions to the knowledge of the landscape in Troy", 1879) and Alttrojanische Gräber und Schädel ("Old Trojan graves and skulls", 1882).[21][80]

Virchow was an opponent of Darwin's theory of evolution,[81][82] and particularly skeptical of the emergent thesis of human evolution.[83][84] On 22 September 1877, he delivered a public address entitled "The Freedom of Science in the Modern State" before the Congress of German Naturalist and Physicians in Munich. There he spoke against the teaching of the theory of evolution in schools, arguing that it was as yet an unproven hypothesis that lacked empirical foundations and that, therefore, its teaching would negatively affect scientific studies.[85][86] Ernst Haeckel, who had been Virchow's student, later reported that his former professor said that "it is quite certain that man did not descend from the apes...not caring in the least that now almost all experts of good judgment hold the opposite conviction."[87]

Virchow became one of the leading opponents on the debate over the authenticity of Neanderthal, discovered in 1856, as distinct species and ancestral to modern humans. He himself examined the original fossil in 1872, and presented his observations before the Berliner Gesellschaft für Anthropologie, Ethnologie und Urgeschichte.[7] He stated that the Neanderthal had not been a primitive form of human, but an abnormal human being, who, judging by the shape of his skull, had been injured and deformed, and considering the unusual shape of his bones, had been arthritic, rickety, and feeble.[88][89][90] With such an authority, the fossil was rejected as new species. With this reasoning, Virchow "judged Darwin an ignoramus and Haeckel a fool and was loud and frequent in the publication of these judgments."[91]

On 22 September 1877, at the Fiftieth Conference of the German Association of Naturalists and Physician held in Munich, Haeckel pleaded for introducing evolution in the public school curricula, and tried to dissociate Darwinism from social Darwinism.[92] His campaign was because of Herman Müller, a school teacher who was banned because of his teaching a year earlier on the inanimate origin of life from carbon. This resulted in prolonged public debate with Virchow. A few days later Virchow responded that Darwinism was only a hypothesis, and morally dangerous to students. This severe criticism of Darwinism was immediately taken up by the London Times, from which further debates erupted among English scholars. Haeckel wrote his arguments in the October issue of Nature titled "The Present Position of Evolution Theory", to which Virchow responded in the next issue with an article "The Liberty of Science in the Modern State".[93] The debate led Haeckel to write a full book Freedom in Science and Teaching in 1879. That year the issue was discussed in the Prussian House of Representatives and the verdict was in favour of Virchow. In 1882 the Prussian education policy officially excluded natural history in schools.[94]

Years later, the noted German physician Carl Ludwig Schleich, would recall a conversation he held with Virchow, who was a close friend of his: "...On to the subject of Darwinism. 'I don't believe in all this,' Virchow told me. 'if I lie on my sofa and blow the possibilities away from me, as another man may blow the smoke of his cigar, I can, of course, sympathize with such dreams. But they don't stand the test of knowledge. Haeckel is a fool. That will be apparent one day. As far as that goes, if anything like transmutation did occur it could only happen in the course of pathological degeneration!'"[95]

Virchow's ultimate opinion about evolution was reported a year before he died; in his own words:

The intermediate form is unimaginable save in a dream... We cannot teach or consent that it is an achievement that man descended from the ape or other animal.

— Homiletic Review, January, (1901)[96][97]

Virchow's anti-evolutionism, like that of Albert von Kölliker and Thomas Brown, did not come from religion, since he was not a believer.[14]

Virchow believed that Haeckel's monist propagation of social Darwinism was in its nature politically dangerous and anti-democratic, and he also criticized it because he saw it as related to the emergent socialist movement in Germany, ideas about cultural superiority,[98][99][100] and militarism.[101] In 1885, he launched a study of craniometry, which gave surprising results contradictory to contemporary scientific racist theories on the "Aryan race", leading him to denounce the "Nordic mysticism" at the 1885 Anthropology Congress in Karlsruhe. Josef Kollmann, a collaborator of Virchow, stated at the same congress that the people of Europe, be they German, Italian, English or French, belonged to a "mixture of various races", further declaring that the "results of craniology" led to a "struggle against any theory concerning the superiority of this or that European race" over others.[102] He analysed the hair, skin, and eye colour of 6,758,827 schoolchildren to identify the Jews and Aryans. His findings, published in 1886 and concluding that there could be neither a Jewish nor a German race, were regarded as a blow to anti-Semitism and the existence of an "Aryan race".[13][103]

Virchow did not believe in the germ theory of diseases, as advocated by Louis Pasteur and Robert Koch. He proposed that diseases came from abnormal activities inside the cells, not from outside pathogens.[60] He believed that epidemics were social in origin, and the way to combat epidemics was political, not medical. He regarded germ theory as a hindrance to prevention and cure. He considered social factors such as poverty major causes of disease.[104] He even attacked Koch's and Ignaz Semmelweis' policy of handwashing as an antiseptic practice.[62] He postulated that germs were only using infected organs as habitats, but were not the cause, and stated, "If I could live my life over again, I would devote it to proving that germs seek their natural habitat: diseased tissue, rather than being the cause of diseased tissue".[105]

As a co-founder and member of the liberal party Deutsche Fortschrittspartei, he was a leading political antagonist of Bismarck. He was opposed to Bismarck's excessive military budget, which angered Bismarck sufficiently that he challenged Virchow to a duel in 1865.[21] One version of the events has Virchow declining because he considered dueling an uncivilized way to solve a conflict. A second version has passed into legend, but was well documented in the contemporary scientific literature. It has Virchow, being the one challenged and therefore entitled to choose the weapons, selecting two pork sausages, one loaded with Trichinella larvae, the other safe; Bismarck declined.[60][114][115]

Virchow supported Bismarck in an attempt to reduce the political and social influence of the Catholic Church, between 1871 and 1887.[116] He remarked that the movement was acquiring "the character of a great struggle in the interest of humanity". He called it Kulturkampf ("culture struggle")[6] during the discussion of Paul Ludwig Falk's May Laws (Maigesetze).[117] Virchow was respected in Masonic circles,[118] and according to one source[119] may have been a freemason, though no official record of this has been found.

The tomb of Rudolf and Rose Virchow at Alter St.-Matthäus-Kirchhof

Virchow broke his thigh bone on 4 January 1902, jumping off a running streetcar while exiting the electric tramway. Although he anticipated full recovery, the fractured femur never healed, and restricted his physical activity. His health gradually deteriorated and he died of heart failure after eight months, on 5 September 1902, in Berlin.[16][121] A state funeral was held on 9 September in the Assembly Room of the Magistracy in the Berlin Town Hall, which was decorated with laurels, palms and flowers. He was buried in the Alter St.-Matthäus-Kirchhof in Schöneberg, Berlin.[122] His tomb was shared by his wife on 21 February 1913.[123]