6; 



ences which distinguish Koch's work from that of Klebs 

 and of Pasteur. The latter seem to assume the parasitic 

 origin of the infectious diseases, and their deductions are 

 but too often partially based upon such assumption. 

 Koch assumes nothing, furnishes ocular demonstration 

 of his assertions and uses all his influence, by precept 

 and example, to raise this subject of bacterial investiga- 

 tion from the mire of uncertainty, doubt, skepticism, and 

 contempt to the firm basis of exact science. For our 

 patience has been so sorely tried, our confidence so often 

 abused, that we have acquired a certain indifference to 

 bacterial discoveries ; we often fail to discriminate ac- 

 cording to the evidence furnished, and regard all alike as 

 essentially uncertain and obscure. 



In this failure to discriminate between evidence and 

 evidence, between assertions and assertions ; in this fail- 

 ure to distinguish between a deduction and a demonstra- 

 tion, is to be found, in part at least, the explanation of 

 the remarkable attitude, or rather variety of attitudes, 

 maintained by the medical public of our land, and of our 

 land only, on the question to be next discussed tuber- 

 culosis. All pathologists worthy of the name, and I be- 

 lieve all others also, are agreed that the miliary tuber- 

 culosis of man is anatomically identical with the disease 

 caused by the same name in rabbits, guinea-pigs, dogs, 

 and cats ; and that pulmonary consumption results from 

 the aggregation and degeneration of miliary tubercles. 



From the earliest times there seems to have been a 

 suspicion among medical men that tuberculosis is a com- 

 municable disease ; now and then an instance was ob- 

 served in which a previously healthy individual, of non- 

 consumptive stock, became tuberculous after assuming 

 an intimate relation as of husband or wife to a con- 

 sumptive individual ; and domestic animals, even those 

 not particularly susceptible to the disease, such as dogs, 

 became in some instances consumptive after close attend- 

 ance upon a human subject previously so afflicted. Yet 

 the evidence of such cases, however suggestive, was not 

 decisive ; so difficult is the proof of inoculation, so insid- 



