VETERINARY PROBLEMS. 17 



an enormous inflammatory and gangrenous swelling is pro- 

 duced in this location which may cause death, but without 

 a trace of inflammation of the lungs. If the virus is inserted 

 in the end of the tail there is again a local swelling and in- 

 flammation ; but owing to the nature of the tissues and the 

 distance from the vital organs the consequences are far less 

 serious, and but two or three die out of every hundred oper- 

 ated upon. Curious as it may appear, this slight swelling at 

 the end of the tail, which disappears entirely within a few 

 weeks, is still sufficient to grant a very complete immunity 

 from this disease in the future ; and inoculations into the tis- 

 sues of the neck, which almost invariably produce death in 

 animals which have not been operated upon in the tail, are no 

 longer dangerous, and scarcely produce appreciable results, 

 while exposure to sick animals is equally harmless. But 

 even with this disease inoculation has its disadvantao;es. The 

 virus multiplies at the point of inoculation ; serum charged 

 with it exudes at and about the wound and is scattered by 

 the movements of the tail, over the stable floors, over the 

 attendants, over other animals, and possibly into the milk 

 pail. While, therefore, the animal obtains an immunity, it is 

 only at the expense of renewing the infection of the stable and 

 making it all the more necessary to keep up the operation with 

 every new arrival. When the authorities of New York and 

 New Jersey permit the inoculation of animals with lung 

 plague virus as the}'' are now doing, we can understand from 

 this what will be the result : animals may be taken to in- 

 fected stables with comparative safety, but there will remain 

 infected stables as long as this operation is practised. • 



The discovery that those people who contracted bovine 

 variola were afterwards exempt from small-pox was a great 

 advance, not only from the practical standpoint of the pre- 

 vention of this disease, but considered scientifically in its 

 bearing on other diseases. The variola of cattle seems to 

 be a modified form of human variola ; or, in other words, the 

 virus of small-pox after it has multiplied for a certain length 

 of time in the body of the cow loses much of its virulence, 

 produces a very mild disease, and is even changed from a 

 virus which multiplies throughout the whole economy, to one 

 which multiplies only at the point where it is inserted. The 



