DISEASES OF THE BLOOD. 139 



affection, animals fall sick, are feverisli for a short time, 

 and then resume their originally healthy state. Probably 

 they have been subjected to the action of the virus, and 

 nature has enabled them to throw it off. Some autho- 

 rities, during the more acute periods of the attack, recom- 

 mend application of blisters to the side, a cathartic dose, 

 and even bleeding when performed early. It is question- 

 able whether these measures prove beneficial, except by 

 debilitating the patient, and so shortening the case. More 

 success seems to have attended the administration of mineral 

 tonics, especially the Cupri Ammonio- Sulphas, together with 

 stimulants, eliminatives, and hyposulphites ; also attention 

 must be paid to careful nursing. Isolation of diseased and 

 suspected animals, and disinfection, are most useful prophy- 

 lactic means, and the administration of iron tonics has been 

 suggested. It is often best in the long run to stamp out an 

 outbreak. The Contagious Diseases (Animals) Acts require 

 special measures for eradication and prevention of spread. 



An animal after recovery should not be reintroduced 

 into the herd before the lapse of three months, and the 

 virus is said to be potent for as much as six months after 

 the animaVs death. 



Inoculation, — It had been noticed that one attack of 

 certain blood diseases ensures immunity more or less 

 permanent against a second of the same disorder. It was 

 therefore suggested that a first attack of a mild character 

 might be artificially induced by direct introduction of 

 morbific material into the system. This was first tried 

 with smallpox in man, and succeeded in so far as im- 

 munity was secured ; but the disease as artificially gene- 

 rated proved severe, communicable, and frequently even 

 fatal. The practice of inoculation was falling into dis- 

 repute when Jenner's observations of the diseases of 

 animals in relation to those of man enabled him to dis- 

 cover vaccination. Here an artificially induced attack of 

 a very mild disorder acts as a prophylactic against a more 

 severe one of not the same, but a closely allied disease. 

 Vaccination has been tried haphazard for certain diseases 

 of lower animals, in no case with markedly beneficial 



