No. «. DEPAllTMENT OK AGRICULTURE. 467 



gained in coiillkt with other pestilences, and aim, with clear recog- 

 nition of the purpose and resolute avoidance of wrong roads, at strik- 

 ing the evil at its root, then the battle against tuberculosis, which 

 has been so energetically begun, cannot fail to have a victorious 

 issue." 



KEPLY OF LOKD LISTEK TO PKOF. KOCH. 



He said that the discourse they had liste«od lo was full of pro- 

 found interest from the beginning to the end. But what had chiefly 

 riveted their attention had been the startling thesis that bovine 

 tubercle could not develop in the human body. This was a matter 

 of enormous practical importance because if this conclusion were 

 sound it would greatly simplify their preventive measures, but it 

 would be a very serious and grievous thiug if the rules now in force 

 for securing purity of milk supply should be relaxed and it should 

 turn out after all that the conclusion was erroneous. For his own 

 part he thought the evidence adduced by Dr. Koch to show that 

 human tubercle could not be communicated to bovine animals very 

 inconclusive. At the same time he agreed with him that in a matter 

 of such great importance further inquiry was desirable. But even 

 if that were established it would by no means oecessarily follow that 

 bovine tubercle could not be communicated to man. He took in 

 illustration the case of variola. Attempts to inoculate human small- 

 pox into the calf had been so very rarely successful that eminent 

 pathologists had concluded that small-pox and cow-pox were two 

 entirely' different diseases. We now know that this was an entire 

 mistake; that cow-pox was small-pox modified by passing through 

 the cow. He referred to some very instructive experiments by Dr. 

 Monckton Copeman, vvho entirely failed to inoculate human small- 

 pox into the calf but invariably succeeded in inoculating it into the 

 monkey, asid was as invariably successful when he introduced matter 

 from the pustules in the monkey into the calf, the result being or- 

 dinary cow-pox which could be used for vaccinating children. It 

 might be that some species of animals might serve as an inter- 

 mediary host for tubercle between man and the bovine species. Or 

 it might turn out that, if a sufficient number of experiments were 

 made, human tubercle might prove occasiooaily transmissible to 

 the bovine animal, as small-pox was in rare instances to the calf, 

 and that the bovine tubercle so produced might be transmissible 

 to man, as was the virus of vaccine. The evidence, necessarily in- 

 direct, on which Koch relied as showing that bovine tubercle could 

 not be transmitted to man, did not seem at all conclusive. It con- 

 sisted mainly in the alleged rarit}' of primary tuberculous intestinal 

 lesions in children in spite of the multitudes of tubercle bacilli 

 swallowed by them in milk. Even if it were admitted that primary 



