OBSERVATIONS AND EXPERIMENTS ON INTESTINAL 



TRICHINA 



By Benjamin Schwartz 

 Zoological Division, Bureau of Animal Industry, United States Department of Agri- 

 culture 



SCOPS OF WORK 



Although Trichinella spiralis has been studied by many investigators, 

 the literature on the subject is almost exclusively devoted to the mor- 

 phology and life history of the parasites and their relation to the disease 

 which they produce in man and in other mammals. Several investiga- 

 tors have recorded some casual observations on the physiology of these 

 parasites, particularly with reference to the resistance of the encysted 

 larvae to unfavorable conditions. No attempt has heretofore been 

 made, however, to present a systematic account of the behavior of these 

 organisms under the influence of various physical and chemical stimuli 

 at different stages of their life history. Recently Ransom (6y in the 

 course of a report of an investigation on the effects of refrigeration on 

 the encysted larvae of Trichinella spiralis has presented some interesting 

 data relative to their behavior when freed from their cysts by artificial 

 digestion. Ransom and the present writer have continued these inves- 

 tigations and have obtained a considerable amount of data ^ on the re- 

 sistance of the larvae to high temperatures and to various physical and 

 chemical agents. 



Inasmuch as little has been known heretofore concerning the physio- 

 logical processes of the parasites concomitant with their growth in the 

 small intestine, it appeared to the writer that observations and experi- 

 ments on the intestinal forms, with special reference to their behavior 

 under various conditions, might yield some useful information. The 

 present paper embodies the results of this work and also includes observa- 

 tions on the molting of the larvae in vitro, a phenomenon which, so far 

 as the writer is aware, has not been hitherto recorded. 



METHODS OF STUDY 



In nearly all the observations and experiments recorded in this paper 

 the parasites were obtained from albino and hooded rats which were 

 artificially infected by feeding ground-up trichinous pork. It was found 

 that after being kept on a vegetable diet for several days, rats devour 

 meat very readily even though it is badly decayed. In some respects 



' Reference is made by number (italic) to "Literature cited," p. 482. 

 2 These results have not yet been published. 



Journal of Agricultural Research. Vol. XV, No. 8 



Washington, D. C. Nov. 2s. 1918 



qj Key No. A-44 



8.3817°— 18— ^1 



(467) 



