130 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



COLLECTION OF PARASITES. 



During the year 475 specimens were added to the collection of 

 parasites maintained by the bureau for study and reference. One of 

 the most interesting specimens received was a piece of horse muscle 

 infested with a larval tapeworm resembling the intermediate stage 

 of Tarda solium. A similar parasite has not heretofore been recorded 

 from the horse. 



ZOOLOGICAL INVESTIGATIONS RELATING TO MEAT INSPECTION. 



Investigations on the effects of curing upon the vitality of trichina? 

 have been continued. As an alternative to refrigeration for 20 days 

 at 5° F., certain curing processes have been permitted in establish- 

 ments under Federal meat inspection in the preparation of hams and 

 sausages of kinds customarily eaten without cooking. These methods 

 are being subjected to repeated tests supplementing those originally 

 made, in order that the methods finally adopted may be established 

 on the firmest possible basis as to their adequacy in destroying the 

 vitality of trichina?. During the year about 150 tests of this kind 

 were made. As a result of these tests it has been found necessary to 

 discontinue one of the curing processes for hams because it was found 

 that this process did not invariably destroy the vitality of trichina?. 



MISCELLANEOUS INVESTIGATIONS OF ANIMAL PARASITES. 



Further investigations of the life histories of tapeworms of sheep 

 and other herbivorous animals have failed to show how these para- 

 sites are transmitted. 



The gapeworm of turkeys, generally considered to be of the same 

 species as the form occurring in chickens, although usually consider- 

 ably larger, has been definitely shown to be transmissible to chickens. 

 Young chickens begin to show symptoms of gapes in about a week 

 after feeding with cultures containing the embryos of the parasite. 

 Full-grown turkeys harboring gapeworms show no recognizable 

 symptoms. Infested turkeys are probably in many cases an impor- 

 tant source from which chickens become infected with gapeworm 

 disease. Young stages of the gapeworm have been found in various 

 organs following the feeding of cultures to experimental chickens, 

 and a number of gaps in our knowledge of the way in which the para- 

 site reaches its location in the air passages have been filled up. The 

 evidence thus far obtained tends to show that the young worms do 

 not migrate, after hatching in the alimentary tract, up the esophagus 

 and down into the trachea, as supposed by some investigators, but 

 that they are probably distributed by the circulation or by direct 

 migration through the body cavity and into the lungs. 



Among various miscellaneous investigations may be mentioned 

 studies of certain species of flukes, roundworms of horses, resistance 

 of the eggs of tapeworms to different chemicals, parasites of live 

 stock in the island of Guam, and certain phenomena in the biologi- 

 cal relations between parasites and their hosts. 



Sixty-five imported sheep dogs were examined in quarantine for 

 the presence of tapeworms transmissible to live stock, and 9 were 

 found to be infested and were subjected to anthelmintic treatment 

 before they were released. 



