188 ON INOCULATION AS A MEANS FOR THE 



according to the establislied law, produce lung disease of the 

 particular type, though in a milder degree. Instead of this we 

 have as the usual result a small local sore, which heals rapidly, 

 and, in many cases, gives rise to no constitutional disturbance; 

 and in exceptional cases, when the local signs are severe, such as 

 extreme swelling of the tail and regions of the hips, anus, &c., 

 accompanied by gangrene, loss of the tail and muscular substance, 

 the lungs may become the seat of a secondary disease, in wliich 

 abscess and gangrene are associated. There is, therefore, not the 

 slightest analogy in the conditions. Pleuro-pneumonia consists of 

 a peculiar inflammation of the whole of one or both lungs, but 

 the lung disease from inoculation by the so-called pulmonary 

 virus is nothing less than pyasmia. the result of the absorption 

 oi putrid elements, and the effect a blood poisoning, generally of 

 rapid nature. Instead of being general, or spread through the 

 whole of the organ, it is isolated and situate within a mass of 

 healthy tissue. 



Considerable stress has been laid upon probability of disease 

 being already in an incubative stage in those animals which fall 

 victims to pleuro-pneumonia immediately after inoculation. Of 

 this there can be no doubt, and in this fact we recoiiuise another 

 grave reason for doubting the existence of the virus, for in accord- 

 ance with the assumed law, are we not justified in expecting that 

 the malady will lose much of its intensity and danger by inocu- 

 lation. But we have seen repeatedly this is by no means the 

 case. In one herd of cattle which we assisted to inoculate, these 

 effects were painfully developed. The stock consisted of upwards 

 of 5i) head of two-year-olds and upwards. On our arrival a cow 

 going through a tolerably mild form of the disease was slaughtered, 

 and the fluid extracted from the lungs was injected, by means of 

 a syringe, beneath the skin on the lower end of the tail of each 

 ■of the others. In a few days another was seized and died, and 

 at different periods, varying from days to weeks, others fell vic- 

 tims to the genuine disease, pleuro-pneumonia, but none showed 

 any ill effects from the inoculation. 



We have here one out of many proofs Avhich might be given, 

 that when pleuro-pneumonia is once within the system inocula- 

 tion does not always lessen its effects ; and further, it does not 

 always prevent the animal afterwards becoming infected. In 

 the instance given, the disease was at first brought by one 

 animal ; this infects others, and they are inoculated while they 

 are infected — that is, before any appreciable signs of disease are 

 to be observed ; but there are others not infected, and these are 

 inoculated also. Subsequently the disease is developed in the 

 first, and they manufacture more ]^oison germs, Avhich float 

 thi'ough the air and reach the healthy cattle ; at length they 

 successively fall victims to ordinary exudative pleuro-pneumonia 



