INTRODUCTION. 25 



opinion held by him and the accuracy of his own 

 views, viz., that it was always through the access of 

 organisms from without that decomposition primarily 

 originates. (See page 18.) 



Under the most careful precautions, against which 

 no objection could be raised, these experiments of Bill- 

 roth and Tiegel were repeated by Pasteur, Burdon- 

 Sanderson, and Klebs, but with failure in each and 

 every instance to demonstrate the presence of bacteria 

 in the healthy living tissues. 



The fundamental researches of Koch (1881) upon 

 pathogenic bacteria and their relation to the infectious 

 diseases of animals differed from those of preceding 

 investigators in many important respects. The scien- 

 tific methods of analysis with which each and every 

 obscure problem was met as it arose served at once to 

 distinguish the worker as a pioneer in this hitherto 

 but partly cultivated domain. The outcome of these 

 experiments was the establishment of a foundation upon 

 which bacteriology of the future was to rest. He, for 

 the first time, demonstrated that distinct varieties of 

 infection, as evidenced by anatomical changes, are due 

 in many cases to the activities of particular specific 

 organisms, and that by proper methods it is possible to 

 isolate these organisms in pure culture, to cultivate them 

 indefinitely, to reproduce the conditions by inoculation 

 of these pure cultures into susceptible animals, and, by 

 continuous inoculation from an infected to a healthy ani- 

 mal, to continue the disease at will. By the methods 

 that he employed he demonstrated a series of separate 

 and distinct diseases that can be produced in mice and 

 rabbits by the injection into their tissues of putrid 

 substances. The diseases known as septicaemia of mice. 



