Inoculation for Pleuro- Pneumonia in Cattle, 263 



dangerous than it would be if introduced into the system of any 

 ordinary animal. The reverse of this is likewise equally true. 

 Thus many a medical student, who perchance may bid fair to 

 occupy an exalted position in his profession, has fallen a sacrifice 

 to a trivial wound received in the dissection of a diseased body, 

 while the veterinary student, on the contrary, from having to 

 dissect our ordinary domesticated animals, rarely suffers from 

 such wounds. This law offers an impediment to, but does not 

 entirely prevent, the conveying of a disease, from animal to animal 

 of a different kind, by inoculation. We have a good example in 

 sheep not being susceptible to the action of the small-pox virus of 

 7nan, although remarkably so to that of their own small-pox, and 

 also of man being susceptible to the virus of Ms small-pox, but 

 not to that of sheep. 



With reference to the decrease in the number of cases of 

 Pleuro-pneumonia at Ruddington since the adoption of inocula- 

 tion, we would observe that great caution should be exercised in 

 coming to an opinion of the cause of the decline of an epizootic, 

 or even an ordinary contagious affection. Circumstances about 

 which we know but little will cause the outbreak of an epizootic 

 disease, and circumstances about which we probably know less will 

 produce its removal. There are periods in the history of Pleuro- 

 pneumonia on Mr. Paget's premises, vv'hen the cattle have been 

 for weeks as free from disease as since they were inoculated. 

 The time, we admit, is longer, but the cause may be the same 



It was acknowledged, even in Hasselt, that they had had as 

 little disease in some summers, prior to the employment of inocu- 

 lation, as during the last when the system had reached its climax. 

 In proof that inoculation was not the sole cause of this freedom, 

 is the fact that the cattle of the distillers who objected to have 

 the operation performed continued as healthy as those of others 

 who did not so object. What we contend for is, that, as there 

 are no specific local effects produced by inoculation, so protection 

 does not depend on the special action of a special virus on the 

 organism, as is the case with the vaccine and other similar dis- 

 eases. 



Protection we believe to be more apparent than real, and 

 that it results m^ainly from simple local irritation. When this 

 and the accompanying inflammation are slight, the animal is in 

 constant danger of an attack of Pleuro-pneumonia, even whilst 

 the local action exists : when greater, a simple issue is pro- 

 duced, the effects of which, as a drain on the system, are mere 

 lasting and therefore likely to be miore beneficial ; but vrhen 

 carried to the fullest extent, then the anim.al's life is endangered 

 Irom another cause, namely, from the sphacelitic action Avhich 

 ensues. With regard to the utility of simple issues or setons, it 



