BUREAU OF ANIMAL, INDUSTRY. 271 



showed typical lesions of hog cholera. No more convincing proof of 

 the efficacy of this serum could be obtained than is afforded by this 

 experiment. 



A considerable amount of experimental work concerning hog 

 cholera has been carried out as opportunity offered. In the previous 

 annual report it was stated that carbolic acid, even in considerable 

 concentration, did not destroy the virulence of hog-cholera blood, 

 although it was sufficient to destroy the ordinary forms of bacteria 

 which are at times present in such blood as contaminations. It was 

 considered desirable to eliminate these foreign bacteria in blood to be 

 used for inoculation simultaneously with the serum, and experiments 

 were carried out with that idea in view. The experiments showed 

 that it Avas perfectly feasible to protect hogs completely from hog 

 cholera, probably for life, by injecting them simultaneously with 

 carbolized hog-cholera blood and anti-hog-cholera serum. It is be- 

 lieved that the use of carbolized hog-cholera blood in connection with 

 the serum will be of distinct advantage when simultaneous inocula- 

 tions are carried out. 



Experiments have shown that the virus of hog cholera is not de- 

 stroyed by a 2 per cent solution of carbolic acid, even after contact 

 witli the disinfectant for two weeks. The practical effect of this is 

 to indicate that carbolic acid should not be used as a disinfectant in 

 the outbreaks of hog cholera, but should be replaced by " liquor 

 cresolis compositus " (U. S. P.) in a 3 per cent solution. 



The Kansas State Agricultural Experiment Station has published 

 bulletins indicating that it had used with some success as a vaccinating 

 agent blood from a horse which had been injected with hog-cholera 

 blood, it being supposed that the residence of the virus of hog cholera 

 in the body of the horse brought an attenuation of the virus, and that 

 the inocufation with this horse blood, drawn at a ^iven time after 

 inoculation, conferred an active immunity upon the injected hog. The 

 Bureau undertook to test this point, and while our experiments have 

 been carried out with only one horse, the results were entirely nega- 

 tive, and it was not considered that we were warranted in pursuing 

 tliis line of experiment further. We have likewise failed to procure 

 a potent serum by injecting horses with blood taken from hogs sick 

 of hog cholera. 



Efforts to determine the nature of the pathogenic agent present in 

 the blood of sick hogs and responsible for hog cholera have been con- 

 tinued, but no positive conclusions have been reached. 



TUBERCULIN AND MALLEIN. 



Tuberculin for the diagnosis of tuberculosis in cattle was prepared 

 and sent out during the fiscal year to the amount of 349,272 doses, 

 an increase of more than 38 per cent over the amount distributed the 

 year previous. This is undoubtedly due to the increased interest 

 which health officials are sliowing in the subject of tuberculosis, and 

 also to their recognition of the fact that the tuberculous cow is a seri- 

 ous menace to public health. The tuberculin was distributed to state, 

 countv. and municipal officials. 



IVIallein to the amount of 73.346 doses, for the diagnosis of glanders 

 in horses, was also prepared and distributed. 



