470 Journal of Agricultural Research voi. xv.no. s 



Ransom (<5) has shown that after trichinous meat has been digested 

 at a temperature of 37° to 40° C. in an acidified solution of scale pepsin 

 the parasites are liberated from their cysts. When taken out of the 

 incubator the larvae in the artificial gastric juice are found to be very active. 

 Their activities are due to vigorous muscular movements, which propel 

 the parasites and are thus locomotory in nature. Assuming that after 

 liberation from their cysts in the stomach of a rat or other host the 

 larvae exhibit the same activity, it is probable that their own movements 

 hasten and guide their transfer to the intestine. Chemotactic influences 

 may play an important part in the migration of the larvae from the 

 stomach to the intestine. 



The nonliving larvae apparently remain in the lumen of the stomach 

 until they are forced into the intestines with the chyle. 



EFFECTS OF GASTRIC DIGESTION ON THE LARV^ 



Ransom (6) found that after artificial digestion the decapsuled larvae 

 may be kept active for over three weeks in a physiological salt solution. 

 Ransom and the writer kept decapsuled larvae alive in Ringer's 

 fluid at a temperature of about 10° C. for seven weeks, at the end of 

 which period they showed activity on a warm stage.^ At body tempera- 

 ture the life of the decapsuled larvae kept in vitro is brief according to 

 the writer's observations, seldom exceeding 48 hours. But whether 

 the larvae survive several weeks or several hours, they neither in- 

 crease in size nor exhibit any other morphological changes which can 

 be attributed to growth. After artificial digestion they can maintain 

 their vitality outside of the host for varying periods, depending on the 

 temperature and osmotic pressure of the medium in which they are 

 kept, but they do not resume their processes of growth and morpho- 

 genesis, which came to a halt coincident with encystment. 



The question arises whether natural gastric digestion not only releases 

 the parasites from their cysts, as artificial digestion does, but also in 

 some way stimulates them to growth and development. That is, may 

 not the impulse which leads to growth originate in the stomach of the 

 host, the intestine merely supplying a suitable environment for con- 

 tinuation of the process begun in the stomach? Within four hours 

 after feeding trichinous meat the writer isolated several larvae from the 

 small intestine. They were tightly coiled and apparently quite unaffected 

 by their passage through the stomach and brief sojourn in the intestine. 

 After being transferred to a physiological salt solution they were placed 

 in a refrigerator at 10° C. They remained tightly coiled in the same 

 way as lan^ae obtained by artificial digestion. 



Coiled trichinae obtained from the intestine 15 hours, 18 hours, and 

 24 hours after feeding trichinous meat were similarly isolated and kept 



' The results of these experiments have not yet been published. 



