BUREAU OF ANIMAX. INDUSTRY. 277 



During the year a fairly large number of samples of commercial 

 butter ^yere tested for tubercle bacilli. The tests, among other things, 

 showed that commercial butter varies greatly as to the amount of 

 water, curd, salt, fat, filth, bacteria, etc., which it contains. Six of 

 the samples examined were found on microscopic examination to con- 

 tain acid-fast bacteria that were indistinguishable, optically, from 

 tubercle bacilli. Guinea-pig injections with samples of the butter 

 caused tuberculosis in only one instance, but the injection tests were 

 made with such very minute quantities that they can not be said to 

 have given wholly reliable results. This investigation will be 

 r'epeated and an effort made to distinguish between butter derived 

 from raw and from pasteurized cream. 



A number of samples of commercial tuberculin were tested to de- 

 termine whether they were of sufficient potency for use as diagnostic 

 agents for cattle tuberculosis. It is gratifying to say that all the 

 samples tested were found to be satisfactory. 



For the new year it is planned to make a careful test of the differ- 

 ent methods of applying tuberculin to animals for diagnostic pur- 

 poses, not with the idea that some other method will give better 

 results than the subcutaneous injection which, when honestly and 

 properly applied, has an accuracy that we can not reasonably hope 

 to exceed, but mainly with the idea that some method for applying 

 tuberculin may be found which will answer as a check against those 

 frauds which are at times practiced by unscrupulous dealers in cattle 

 to prevent a reaction from tuberculin even though tuberculosis is 

 present. 



An attempt has been made, by feeding guinea pigs with pasteurized 

 milk from cows affected with udder tuberculosis, to determme whether 

 the dead tubercle bacilli in such milk have an injurious effect on the 

 body. This investigation has not yet given results of a sufficiently 

 definite character to be reported. An effort will be made to study the 

 possibly increased or reduced resistance to tuberculous infection which 

 may be associated with the use of pasteurized infected milk. 



OTHER WORK. 



Hog diseases, Texas fever, cattle ticks, cattle-tick dips, blackleg, 

 glanders, swamp fever, tetanus, cattle mange, infectious abortion, the 

 internal and external parasites of sheep, rabies, and a number of other 

 subjects have received more or less attention at the Experiment 

 Station. 



In addition to cooperative breeding investigations, the Experiment 

 Station has provided the Animal Husbandry Division and other 

 divisions of the Bureau with extensive facilities for independent 

 investigations. As during former years, large numbers of small ex- 

 periment animals and a large amount of forage were raised at the 

 station, and a considerable quantity of material in the form of black- 

 leg meat, normal and other sera, milk, etc., were supplied to the city 

 laboratories of the Bureau. 



