ii6 CONTEMPORARY SCIENCE 



contagium vivim or animatum and hence of an invisible 

 form of life as the initiator of the condition, can be traced 

 far back in the written records of human events. And 

 yet it was not until about 1850 that a microscopic body, 

 which we would now call a bacterium, was actually de- 

 tected in the blood of a sick animal. The anthrax bacillus, 

 as it has since been named, which is now recognized as 

 the inciting microbe of splenic fever, was destined to play 

 a leading part in the development of the future science 

 of bacteriology, but at this early period its full meaning 

 was not perceived. When, however, in 1863 Davaine 

 succeeded in communicating splenic fever to a healthy 

 animal by the direct inoculation of blood containing the 

 anthrax bacillus, the science of bacteriology may be said 

 to have been born. 



The dates are significant to one who wishes to follow 

 the march of events which brought the greatest master 

 of all, Pasteur, into the field of microbiology and led him 

 on to the study of the infectious diseases, first of animals 

 and then of man. For on looking backward we find that 

 coincidental with Davaine's epochal experiments, Pas- 

 teur was already engaged on those studies of fermenta- 

 tion and putrefaction which were not only to set our 

 conception of those processes on a secure biological foun- 

 dation, but as an important side effect were to demolish, 

 once and forever, the elaborately constructed but inse- 

 curely based doctrine of the spontaneous generation of 

 microscopic forms of life. 



For Pasteur it was but a step, although for us one 

 of the highest importance, from the studies in fermenta- 

 tion and putrefaction to those on the infectious diseases 

 in which, indeed, the great triumphs he achieved consist 

 far less in the detection of new kinds of microbes to which 

 the various contagious diseases might be described, than 

 in his fundamental discoveries in immunology, or the 

 science of the specific prevention of disease. 



This work in the field of immunology, first opened t<? 



