8 HISTORICAL OUTLINE 



desired greatly that his discoveries should benefit mankind in general, France in 

 particular, and, if possible, his neighbours in the first place. Thus we find him 

 investigating with enthusiastic care the troubles of the local vintners or brewers, 

 or vinegar-makers, and many of his memoirs are devoted to the diseases of wines 

 or of beers, and the methods of preventing them. It was in connection with 

 these studies that Pasteur faced a new problem of fundamental importance. He 

 had shown that ferments were living organisms, that they were specific, that they 

 were reproduced from parent forms and not by spontaneous generation. He was 

 now faced with the problem as to whether one species could change into another, 

 in particular whether mycoderma vini could change into the ordinary yeast of 

 wine. Deceived on this point at first, he resorted as usual to rigorous and repeated 

 experiments, and not only demonstrated that this mutation did not occur, but 

 indicated clearly the conditions which led to its apparent occurrence, and the 

 care which must be exercised before accepting any reported variation of this 

 kind. 



Anyone who reads for himself the original memoirs on fermentation and spon- 

 taneous generation (see Vallery-Radot, P., 1922-1933) will realize that the possibility 

 of applying this new knowledge to the elucidation of infective disease was already in 

 Pasteur's mind. It needed only the spur of a request from Dumas to investigate the 

 disease, which was then ruining the silkworm industry in the South of France, to turn 

 his steps permanently towards the study of infective processes. We cannot follow 

 here, even in outline, Pasteur's researches into pebrine, anthrax, chicken cholera, or 

 hydrophobia. Some of them will be referred to in later chapters. We must, how- 

 ever, note certain contributions which Pasteur and his colleagues made to the funda- 

 mental data of bacterial infections. It was Pasteur who showed, in the case of 

 anthrax, that a culture of a pathogenic organism could be passed through succes- 

 sive subcultures, in such a way as to dilute, beyond possibility of significant action, 

 any other material introduced with it into the primary culture from the blood 

 or tissues, and still produce the disease when inoculated into a susceptible animal ; 

 though it is to Koch that priority must be given as regards many points in the 

 demonstration of the nature and action of the anthrax bacillus. It was Pasteur 

 who introduced into bacteriology the conception of virulence and of attenuation, 

 and who demonstrated the fact that an attenuated bacterial culture will act as a 

 vaccine, that is, will confer immunity against subsequent infection with a virulent 

 strain of the same bacterium. For Pasteur, indeed, a vaccine was synonymous 

 with an attenuated culture, as opposed to a virulent culture on the one hand and 

 to a dead culture on the other. It was Pasteur who, in the case of rabies, showed 

 that it was possible to study the virus of an infective disease by animal passage, 

 when the organism could not be cultivated, and even to prepare a perfectly efficient 

 vaccine by using suitably treated animal tissue. 



Thus, throughout a long scientific life, Pasteur was largely concerned with 

 the practical application of knowledge gained during his studies on fermentation. 

 The correct procedure for preparing good wine, good beer, good vinegar, and 

 the methods of preserving them, the control of pebrine, of anthrax, of chicken 

 cholera, of hydrophobia, these were the problems which occupied the last thirty 

 years of his life, and the solution of which made his name a household word. But 

 we shall miss the real significance of his work if we fail to realize that his fertile 

 generalizations were of infinitely more importance for the progress of science 

 than were his successful attacks on these isolated problems. 



