History of Germ Theory

Home , Germ theory of disease

Little worms which propagate plague To accompany the symposium ‘Infectious diseases: problems and challenges’, held at the Royal College of Physicians of Edinburgh in June 2008, Rare Books Librarian John Dallas takes medical texts from the College Library under the microscope and explores the history of germ theory.

marcus terentius VArro Robert Hooke (1635–1703) (116–27 b c ) Micrographia (London, 1665) De re rustica (Venice, 1514) The invention of the microscope The idea that certain diseases were revolutionised the study of caused by minute living creatures infectious diseases. Hooke’s invisible to the human eye goes Micrographia was the first work back more than 2,000 years. The entirely devoted to an account of Roman scholar Marcus Varro was microscopical observations. The director of the imperial library at accurate illustrations (see plate on Rome and the author of the above the left as an example), engraved by work on agriculture. Varro warned Hooke himself, include the first against locating homesteads in the published depiction of a micro- proximity of swamps ‘because there organism. Hooke examined a ‘small are bred certain minute creatures white spot of a hairy mould’ taken which cannot be seen by the eyes, from the sheepskin cover of a book. which float in the air and enter the He called the organism a body through the mouth and nose ‘microscopical mushroom’. and there cause serious diseases’. Mycologists now identify Hooke’s specimen as the microfungus Mucor.

is breeding ground or nursery. Marchamont Needham Although he stated contagion was (1620–1678) effected by ‘small imperceptible Medela medicinae (London, 1665) particles’, Fracastoro never Although Needham practised as a perceived these particles to be physician, he is best known as a living creatures. He did speculate, political writer and pioneer journalist. however, that each disease had Ahead of most of the medical its own specific seminaria, an idea profession, however, Needham that was neglected for more than recognised the importance of 300 years. Kircher’s discoveries and was the first to report on them and Athanasius Kircher translate them into English. This (1602–1680) work has been described as the first Scrutinium physicio-medicum English publication on bacteriology. contagiosae luis, quae pestis dicitur (Rome, 1658) Antoni van Leeuwenhoek Girolamo Fracastoro Kircher was a Jesuit priest and (1632–1723) (1478–1553) scholar who wrote on a wide Microscopical observations De contagione (Venice, 1555) variety of subjects. In 1656 he (Philosophical Transactions of Fracastoro (pictured above) stated attempted to find the cause of a the Royal Society of London) that there were diseases that could virulent outbreak of bubonic plague (London, 1683) be caused by a contagion which by studying the blood of the victims The Dutch shopkeeper Leeuwenhoek ‘passes from one thing to under a microscope. He described (pictured overpage) had an obsession another’. These were transmitted how he found it to be full of ‘little for microscopes and a talent for lens in three ways: by direct contact worms which propagate plague, grinding. For more than 50 years he with the infected, by contact with so very small and unperceivable made important observations in their clothes or carried by the air. except with a very fine every branch of natural science. After Fracastoro described this agent of microscope’. This is regarded to be studying samples of plaque and history contagion as seminaria, a word the first clear statement of the spittle, Leeuwenhoek wrote to the which has often been translated as germ theory of disease based on Royal Society that he found ‘an germs. Its literal meaning, however, microscopical examination. unbelievably great company of living

376 Exhibitions: Little worms which propagate plague

myself was the means of carrying the infection to a great number of women.’ Fifty years before Holmes and Semmelweis, Gordon wrote that he had ‘evident proofs that every person who had been with a patient in the puerperal fever became charged with an atmosphere of infection, which was communicated to every pregnant woman who happened to come within its sphere. This is not an assertion, but a fact.’ He recommended that midwives and doctors should ‘carefully wash themselves, and to get their apparel properly fumigated before it be put animalcules… in such enormous on again’. numbers, that all the water … seemed to be alive’. Although he John Goodsir (1814–1867) never connected these creatures History of a case in which a fluid with disease, his observations and periodically ejected from the drawings are the first recorded stomach contained vegetable descriptions of micro-organisms. organisms of an undescribed form (Edinburgh Medical Sir John Pringle Surgery Journal) (Edinburgh, 1842) (1707–1782) It has been suggested that the first Observations on the diseases of person to recognise and cure a the army (4th ed) (London, 1764) bacterial infection was the Scottish Pringle’s work established the basic surgeon John Goodsir (pictured principles of the sanitation and above). Examining the vomit of a ventilation of hospital wards and sick boy under the microscope, military quarters. It also contains the Goodsir identified a vegetable first use of the word ‘antiseptic’. In organism as the cause of the disease. early editions Pringle had conceived He named this organism Sarcina contagion as due to ‘putrid ventriculi and successfully treated the exhalations from the humours’, but Sir Henry Holland patient with sodium hyposulphite by the fourth edition he had (1788–1873) and weak carbolic acid. ‘perused the curious dissertation, Medical notes and reflections published by Linnaeus, in favour of (London, 1839) Louis Pasteur (1822–1895) Kircher’s system of contagion by The belief in poisonous miasmas still Mémoire sur la fermentation animalcula, [arguing that] it seems prevailed, but the idea that disease appelée lactique (Paris, 1857) reasonable to suspend all was caused by micro-organisms began Pasteur’s discoveries on hypotheses, till that matter is further to find support. Henry Holland fermentation in wine, beer and milk inquired into’. He then writes that (pictured above), physician to Queen demonstrated that it was micro- scabies is ‘best accounted for by Victoria, wrote: ‘We have sufficient organisms in the atmosphere that Leeuwenhoek, from certain small proof through recent discoveries, that produced fermentation diseases. insects he discovered in the postules these morbid actions from parasitic This proof of external by the microscope’. animals are much more numerous and contamination was to finally varied than has heretofore been overturn the theory of the history Alexander Gordon believed. It seems certain that spontaneous generation of micro- (1752–1799) future research will still further organisms caused by internal or A treatise on the epidemic increase the number within our systematic imbalances. The report puerperal fever of Aberdeen knowledge, and while indicating, by of his experiments in the above (London, 1795) aid of the microscope, forms more article has been called ‘the Alexander Gordon of Aberdeen was minute than those yet discovered, manifesto of the germ theory’. It the first to suggest that puerperal will in this very minuteness suggest set forth the fundamental concepts fever was contagious. ‘It is a their more extensive agency as from which the science of disagreeable declaration … that I causes of disease.’ microbiology would develop.