Supplement to "Nature," December 23, 1922 



tributor, and it was chiefly his work that led to the 

 so-called " germ theory " of disease, which by 1876 

 became an established fact. Pasteur's work on 

 fermentations showed that different chemical products 

 are the outcome of the activities of particular microbes, 

 subsisting in and utilising the fermentable substances. 

 His observations on the alcoholic, lactic, butyric, 

 acetic, urea fermentations, and the abnormal fermenta- 

 tions of wines and beers, are classic and have remained 

 the teaching of to-day. It was by an accident that 

 he was dragged into the conflict on spontaneous 

 generation and heterogenesis, and in a short time and 

 by unsurpassed technique answered the question in 

 the " not proven " sense. Of his principal paper on 

 this subject published in 1862, Tyndall, himself a great 

 experimenter, has said that " clearness, strength, and 

 caution with consummate skill for their minister were 

 rarely more strikingly displayed than in this im- 

 perishable essay." Pasteur's works on fermentation 

 and on spontaneous generation acted like a leaven on 

 medical thought, and was the principal cause of the 

 immense advances which, shortly afterwards, took 

 place in our ideas of disease causes. In particular 

 his demonstration of " panspermia," the idea that 

 germs abound everywhere, was the origin of the life 

 work of Lister on the protection of wounds from 

 extraneous contamination and his foundation of 

 antiseptic surgery — the greatest advance ever made 

 in medical art. While Lister throughout his life 

 always referred modestly to his own share in the work, 

 it is by no means to be supposed that he was a mere 

 imitator of Pasteur. Lister was the first to visualise 

 the enormous practical importance of Pasteur's work, 

 and himself was the creator and the greatest exponent 

 of the whole antiseptic advance. 



It was also Pasteur's demonstration of specific 

 fermentations that led Davaine (1863) to renew his 

 observations on the bacteridia seen years before by 

 him with Rayer in anthrax blood, and by Pollender 

 and Brauell. Pasteur himself followed all these 

 advances with keen insight and appreciation, and was 

 thereby brought into personal contact with disease 

 processes although he had no medical training. In 

 particular, he spent the later part of his life in elucidat- 

 ing infectious animal diseases like fowl cholera, swine 

 erysipelas, anthrax, and hydrophobia. Not only did 

 he show that these diseases are due to special microbes 

 differing from each other and producing the specific 

 disease, but he was enormously ahead of his time in 

 discovering prophylactic measures by which these 

 diseases can be prevented by inoculation. One of 

 his greatest discoveries — and one which pervades all 

 his later work — was the demonstration that an 

 attenuated living virus, i.e. one no longer capable 



of causing fatal disease — can by inoculation lead to 

 the prevention of fatal disease. As Jennerian inocula- 

 tion of calf lymph belongs essentially to this category, 

 Pasteur proposed to designate the method by the 

 name " vaccination," although, in so doing, the 

 etymological significance of the word was lost. Pasteur 

 was the discoverer of extraordinary forms of microbes 

 which live without air — anaerobes — and himself dis- 

 covered the first disease-producing microbe of this 

 class, namely, Vibrion scptique. Since his time the 

 knowledge of pathogenic anaerobes has grown to a 

 special department of bacteriology. 



By degrees the fundamental doctrine of the specificity 

 of disease became firmly established. The idea first 

 emanated from the fertile mind of P. F. Bretonneau, 

 the French clinician, who in the beginning of the 

 nineteenth century overthrew the prevailing doctrines 

 of Broussais, and showed that diseases vary from 

 differences in cause rather than from the intensity 

 of the cause or the environment. The actual demonstra- 

 tion of specificity in infective disease is one of the great 

 achievements of modern pathology, and was shown 

 in particular by Robert Koch, who in 1876 introduced 

 simple methods for bacterial cultivation which have 

 not been materially altered down to the present time. 

 Koch's principle utilised media {e.g. gelatine) which 

 were fluid at one temperature and solid at another. 

 By disseminating the microbes in the fluid medium 

 and suddenly solidifying it the bacteria were, so to 

 speak, imprisoned and started to grow and in this 

 way " pure cultures " were easily obtained. Viewing 

 Koch's pure cultures in London in 1881 in Lister's 

 laboratory at King's College, Pasteur, turning to Lister, 

 said, " C'est une grande decouverte." It was the 

 application of Koch's method in his own hands and 

 those of his assistants that, in the decade 1880-1890, 

 revolutionised the subject of disease causation, and 

 led to the discovery of more solid facts than had been 

 possible since the dawn of civilisation. 



The discovery of the microbes of tuberculosis, 

 cholera, diphtheria, glanders, and enteric fever in this 

 decade renders it one of the most fertile in the history 

 of medicine, and was the classical period when the 

 science of bacteriology was founded. Since 1890 the 

 current has flowed in another direction, namely, 

 towards the prevention and cure of specific infective 

 disease by specific remedies, and it was here that 

 Pasteur's main work on the effects of attenuated virus 

 led and still leads the way. When one calmly surveys 

 the immense progress of medical science in the last fifty 

 years it will, we think, be admitted by future historians 

 that its progress and success were due largely to the work 

 initiated with so much imagination and carried out with 

 such incomparable technical skill by Louis Pasteur. 



