480 Journal of Agricultural Research voi. xv, no. s 



continued with the hope that a medium may be found in which the larvae 

 will be capable of undergoing the molt that normally occurs a short time 

 after they reach the intestine in the usual course of events when they 

 are swallowed. 



In looking through the literature relating to trichinosis the writer has 

 found but scant references to experiments on the possibility of causing the 

 development of the decapsuled larvae of Trichinella spiralis in vitro. Fiedler 

 (4) placed pieces of trichinous meat in the gut of a freshly killed rabbit. 

 He tied the gut at both ends and placed it in water at a temperature of 25° 

 to 28° R. Within five days the gut was opened but the trichinae appeared to 

 be unafifected. Pagenstecher (5) states that he did not succeed in causing 

 T. spiralis to develop by means of artificial gastric juice. This investi- 

 gator also placed a portion of intestine containing trichinae in a sugar 

 solution at body temperature for 24 hours, which resulted in the death of 

 the worms. Davaine (j) states that he convinced himself that trichinae 

 do not develop outside of the host in water or in any other medium. 



Among the media tried by the writer the following may be mentioned : 

 Pure blood serum (of rodents), blood serum diluted with salt solution, 

 pancreatin dissolved in an alkaline medium, neutral broth, alkaline broth 

 and various sugar broths, mixtures of pancreatin with various broths, 

 and contents from the small intestine mixed with salt solution. The 

 parasites obtained from trichinous meat by artificial digestion were 

 washed in salt solution and in weak alcohol in order to eliminate bacterial 

 decomposition of the media. The latter were inoculated with the para- 

 sites taken up in a sterile pipette with a little sterile salt solution and 

 then placed in an incubator at body temperature. The most favorable 

 results have been obtained with mixtures of blood serum and salt solu- 

 tion and with dextrose broth. In the serum and serum dilutions the 

 larvae lived considerably longer than when kept in physiological salt 

 solution at incubator temperature, exhibited marked activities, and in 

 one case there were indications of molting. Certain changes in structure 

 were noted which can not be definitely described. The cuticle at the 

 anterior end of the worm had entirely disappeared. 



In dextrose broth the larvae were still alive and active after 24 hours 

 at a temperature of 38° C, and continued aUve for two days at room 

 temperature, whereas in plain broth and in other sugar broths, as well 

 as in neutral media, such as various salt solutions, they died before 24 

 hours had elapsed. In one case larvae kept in an alkaline pancreatin 

 solution we^e found to exhibit unusual acivity, including intestinal 

 peristalsis. 



SUMMARY AND CONCLUSIONS 



(i) The larvae of Trichinella spiralis do not linger in the stomach of 

 the host after they are freed from their capsules, but pass into the 

 small intestine. 



