Inoculation fur Pleura- Pneumonia in Cattle. 247 



consequently infer that, in tlie opinion of the Committee, an 

 attack of the malady, subsequent to inoculation, howsoever 

 remote it may be, would not depend on an exposure to the 

 ordinary causes producing it, but on its being incubated at that 

 time. Indirectly, the committee here assert that inoculation is 

 protective to the animal during the remaining period of its life. 

 That such is not their opinion is seen, however, by the 13th 

 conclusion. 



It is unnecessary here to discuss the question of the differences 

 in the period of incubation of different diseases. For the most 

 part they are well understood, and with very few exceptions 

 clearly ascertained ; rarely does the time exceed two or three 

 weeks. It is evident, therefore, that the Committee merely 

 desire to give it as their opinion, that Pleuro-pneumonia, if 

 happening within a very short time of inoculation, was lying 

 dormant in the system of the animal when the operation was 

 performed. In this view of the subject we can coincide ; but 

 this leaves such cases as are named in our first Report,* of 

 animals attacked two months, and three months and a half after 

 inoculation, to be accounted for only on the principle that they 

 were unprotected by inoculation, and therefore it is an argument 

 against the practice. This question will receive further eluci- 

 dation from the facts which will be given in the after part of the 

 present Report, and we will only add that no person acquainted 

 with pleuro-pneumonia would be found bold enough to affirm 

 that the disease is incubated, or, in other words, is slowly 

 advancing to maturity, during so long a time as two or three 

 months, and this without the animal exhibiting any indications 

 of its existence. 



The only other point in the report of the Dutch Commissioners 

 necessary to allude to here is found in the concluding sentence, 

 where the Committee observe that they do not " hesitate to re- 

 commend inoculation under prudent treatment in every case 

 where pulmonary disease has broken out in a herd of cattle or 

 in the neighbourhood." Would that our own experience en- 

 abled us to say the same : for the present, however, we must 

 leave the opinions and the recommendations of the Committee, 

 and pass on to show what conclusions have been come to by 

 other continental investigators. 



In our first Report it will be seen that allusion is made to 

 certain causes which induced the Government of Prussia to 

 delay its official inquiry into the subject. Subsequently, how- 

 ever, it commissioned Dr. S. Ulrich, Veterinary Professor of the 

 Royal Academy at Mogiin, to proceed to Hasselt, and to report 



* See Journal, vol. xiii. p. 382. 



