248 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



positive when the maximuin temperature after injection was at least 

 103.8° F., provided this maximum represented a rise of at least 2° F. 

 above the maximum temperature recorded before injection. In 

 applying this rule to the 8,980 slaughtered cattle it has been found 

 that 550 failed to react, while 8,430 gave a positive reaction. Of the 

 animals which gave a positive reaction, 8,858, or 99.15 per cent, 

 showed lesions of tuberculosis at autopsy. This is considered a 

 remarkably high percentage of accuracy, in view of the fact that this 

 tuberculin was used in general practice in all parts of the country 

 and by a large number of different veterinarians. From these 

 figures, even if unsupported by other evidence, it would appear to 

 be evident that a positive tuberculm reaction is a practically unfailing 

 indication of tuberculosis in the animals tested. 



Up to the present time there has been no satisfactory means of 

 standardizing tuberculin. Such a process is highly desirable, for it 

 has been shown that at times there have been placed on the market 

 tuberculins which w^ere lacking in potency. A study of this subject 

 is now under w'ay in the Biochemic Division. 



During the fiscal year 91,642 doses of mallein for the diagnosis of 

 glanders in horses were sent out to public officers. This represents 

 an increase of approximately 25 per cent as compared with the 

 preceding year. 



HOG CHOLERA. 



In my last report it was stated that considerable time had been 

 devoted to demonstration w^ork in connection with the j>roduction of 

 serum for the prevention of hog cholera, the objects of this work 

 being to demonstrate successfully the value of the serum and thereby 

 to encourage State officials to take up the manufacture of serum for 

 the benefit of farmers, as it was not practicable for the Bureau of 

 Animal Industry to undertake a general distribution to individuals. 

 It now appears that this w^ork has been productive of much good, as 

 21 States, including practically all of those in which hog raising is an 

 important industry, have made provision for serum production, and 

 not less than 200,000 inoculations have already been made by State 

 oiTicials. The results reported have been extremely favorable, and 

 while the number of hogs treated is not large when compared with 

 the total number in tlie United States, sufficient has been done to 

 show that the State officials and the farmers are interested, and it is 

 believed that with further development of the work a great deal of 

 good will be accomplished. 



A demonstration experiment carried out at the Kansas City Stock 

 Yards was described in my last report. During the past year a 

 similar experiment was carried out at South Omaha, Nebr. This 

 experiment was undertaken at the request of State officials and the 

 Nebraska Swine Breeders' Association. The Union Stock Yards 

 Company of South Omaha also offered to cooperate and to bear the 

 expense "incident to the purchase and care of the hogs used in the 

 experiment. Thirty pigs weighing from 40 to 60 pounds were pur- 

 chased from a farm which had been free from hog cholera for several 

 years. These hogs were carried to the stockyards, and on July 23, 

 1910, four of them were injected with blood from hogs sick of hog 

 cholera. These injected pigs, which were placed in a pen by them- 

 selves, became sick on the 28th of July, at which time 18 of the remain- 

 ing pigs were given one dose of the serum, w^hile the other 8 pigs were 



