BACTERIOLOGY 239 



find themselves under favourable conditions. The 

 last point, established by very beautiful and 

 ingenious experimentation, in the teeth of opposed 

 opinion, is by no means the least important. Upon 

 the facts that these unicellular organisms arise from 

 cells similar to themselves and, with certain minor 

 qualifications, may be said always to breed true, 

 are based the modern science of bacteriology, and 

 the definiteness of our present knowledge concerning 

 zymotic diseases. Even when at the early stage 

 just described Pasteur's results were sufficient to 

 convey to a receptive and logical mind like that of 

 Lister an assurance of their future importance to 

 medicine and surgery; but much had yet to be 

 done to convince the sceptical. Pasteur himself, 

 though not trained in medicine, contributed much 

 in his later work towards establishing the import- 

 ance of micro-organisms in disease. The advance 

 made by others in bacteriological technique was, 

 during his lifetime, so great as to leave him almost 

 an amateur among experts in the narrow domain 

 of pure technicalities; but there are few aspects 

 of modern bacteriology which he did not foresee 

 and initiate by pioneer experiments. From studies 

 of wine and beer, which greatly helped French 

 industries, he proceeded to the investigation of an 

 infective silkworm disease, with results of consider- 

 able economic importance. He then investigated 

 certain diseases of farm animals and earned the 

 gratitude of the farmers. Finally he proceeded to 



