THE HISTORY OF BACTERIOLOGY. 451 



the view that these tumors are perhaps not to 

 be attributed at all to micro-parasitic cause, 

 and hence very stringent proof is necessary to 

 produce conviction on this point. 



The whole tendency to search out " specific " 

 germs of disease and fermentations is a relic 

 of the natural history point of view. The no- 

 tion that every specific disease is caused by a 

 specifically constant parasite is in accordance 

 with the ontological wish of many physicians 

 who are thus spared the trouble of further re- 

 flection. There is, in addition, the fact that in 

 courses of instruction we are compelled first to 

 convey to pupils in a methodical manner and 

 by concrete examples a general understand- 

 ing of fazcontagium animatum. An introduc- 

 tion to the subject matter starts necessarily 

 from the specificity of the microbes. In the 

 brief time at the disposal of most students they 

 usually do not, on the basis of their own ob- 

 servations, pass beyond this stage, so that the 

 courses in bacteriology have aided largely in 

 bringing it about that this ontological and thor- 

 oughly unscientific conception of the relations 

 of bacteria to disease has become the common 

 property of physicians. A pedagogical neces- 

 sity has thus directly contributed to impair 

 the scientific training of physicians. 



It is a false premise that the constancy of 



