172 ANNUAL REPORTS OF DEPARTMENT OP AGRICULTURE. 



A supply of stock cultures comprisinf? many of the pathogenic 

 organisms commonly producing disease in animals are kept con- 

 stantly in cultivation and arc at all times available for supplying 

 scientists Avho desire to cultivate a collection of bacteria and for 

 schools that need them for study and comparison. 



ANIMAL PARASITES. 



Some important work has been done with regard to animal para- 

 sites and parasitic diseases. The Zoological Division has worked out 

 the life history of the stomach worm of sheep, a parasite which en- 

 tails a loss of millions of dollars annually to the sheep industry of 

 this country. This loss may be avoided or minimized only by the 

 adoption of preventive and remedial measures based upon a knowl- 

 edge of the life history of the parasite. 



The presence of the gid parasite of sheep in the United States was 

 discovered. The importance of eradicating this parasite has been 

 pointed out, and a careful watch is kept for new centers of infection 

 in order that more stringent measures may be taken in case the para- 

 site should show a tendency to spread beyond its present restricted 

 limits of distribution. 



The common occurrence of a tapeworm cyst in the muscles of sheep 

 has also been discovered. Investigations have shown that this cyst 

 is the intermediate stage of a dog tapeworm, hence not dangerous to 

 man. The presence of these cysts in mutton, however, renders it 

 undesirable as food, and a considerable loss thus results to the meat 

 supply of the country. 



A common stomach worm of the horse has been found to be trans- 

 mitted by the house fly. The infection passes from the manure of 

 infested horses to fly larvae breeding in the manure, and the full- 

 grown flies developing from these larvae in turn transfer the parasites 

 to horses. 



The discovery of the New World hookworm of man and its ex- 

 tensive distribution in the United States was made by a scientist of 

 the Bureau of Animal Industry who has since gone to another 

 branch of the public service. His far-reaching investigations were 

 begun before he left this department. 



Numerous new species of parasites of varying degrees of economic 

 importance have been discovered in the course of the bureau's work in 

 parasitology, and a complete index to the extensive literature con- 

 cerning parasites has been compiled and published. 



BENEFICIAL RESULTS WIDELY DIFFUSED. 



It can readily be seen that the activities and benefits of these 

 scientific investigations extend into every section of the country, and 

 that the work performed does much to check and to overcome the ad- 



