292 VETERINARY HYGIENE 



with salt and water previous to being salted. In the case of dry 

 hides, a method which appears to be effective even in the cases of the 

 more highly resistant anthrax spores is the Seymour-Jones formic- 

 mercury process. This consists in the immersion of the hides for 

 24 to 48 hours in a solution of formic acid and mercury bichloride 

 and subsequent salting. 



Loffler and Frosch found that in most cases in calves and adult 

 cattle immunity is present 2 or 3 weeks after an attack and lasts 

 for at least 5 months. It is said that this immunity is not developed 

 in every case, and Strebel has observed the recurrence of the disease 

 in cattle after 6 to 10 weeks. Loffler and Frosch worked out a 

 method of immunisation which was employed with a certain 

 measure of success in Germany, and which consisted in the simul- 

 taneous inoculation of lymph from the vesicles (usually 1/50 c.c.) 

 and immune serum (10 cc. usually), immunity being established 

 in about 3 weeks. Such a method it need hardly be stated could 

 never be practised in this country owing to the almost certain 

 creation of centres of infection. The use of an immune serum 

 however, might be advocated to save the lives of cattle which have 

 not been in close contact with infection but which could not be 

 safely regarded without suspicion. 



VARIOLA. 



Variola (pox) is the name given to certain specific fevers associ- 

 ated with the presence of lesions which pass through well-defined 

 stages, viz., papule, vesicle, pustule and crustaceous or scab stage. 



Several animals have a definite variola, viz., man, ox, horse, 

 sheep, goat and possibly pig and dog, and a good deal of contro- 

 versy has occurred as to the exact relationship between them. The 

 virus, which is obligatory, is in all cases capable of passing through 

 a bacterial filter. The common idea is that cow-pox or vaccinia 

 and horse-pox are identical, and a modified form of human variola 

 or smallpox. It was noted that cow-pox and horse-pox often 

 occurred under the same circumstances. Liquid from cow-pox 

 vesicles produces a mild disease in man and a resulting immunity 

 to smallpox (Jenner's method of vaccination). On the other hand 

 sheep-pox is not transmissible to man or the ox, and cow-pox or 

 smallpox lymph injected into sheep does not protect against sheep- 

 pox. It is therefore held that sheep-pox is distinct from variola 

 of man, horse and ox. The virus of sheep-pox does not spread 

 naturally, and is difficult to convey experimentally to goats and vice 

 versa. These two variolae are therefore generally regarded as 



