2o8 Journal of Agricultural Research voi. xvii. no. 5 



warm stage. The temperature was held at 54° for a few moments. The 

 worm was inactive at this temperature but resumed its movements when 

 the sHde was cooled. The same worm was reheated to 55° and became 

 entirely motionless at this temperature. The temperature was raised 

 to 55.5° and the slide then cooled. The worm became active again on 

 cooling. 



Another decapsuled larva was heated in the same manner. It became 

 sluggish in its movements and coiled up at a temperature of 48° C. The 

 temperature was raised slowly to 56°, and the slide was allowed to cool as 

 soon as this temperature was attained. The worm resumed its active 

 movements when cooled. In order to check the correctness of the tem- 

 perature indicated by the thermometer in this experiment, some crystals 

 of diphenylamin having a melting point of 54° were placed on a slide 

 under a cover glass and heated on the stage. They melted when-the 

 thermometer registered 54°. A second trial gave the same result. 



On April 7, a decapsuled larva was heated as described above. The 

 temperature was raised slowly to 56° C. and then held for five minutes at 

 56° to 56.5°. When cooled the worm did not resume its movements, its 

 internal structure showed slight disorganization, and it was undoubtedly 

 dead. 



Experiment 2 (March 28, 1914). — Decapsuled trichinae, isolated by 

 artificial digestion from a mixture of meat from three trichinous rats, 

 were heated in a beaker of constantly stirred water over a hot water 

 bath to a maximum of 53.6° C, 10 minutes being required for the tem- 

 perature to rise to this point from 30°. The temperature dropped to 

 46.2° in another 10 minutes, after which 233 larvae were examined at 

 room temperature. All were inactive. Unheated larvae from this lot 

 when examined at room temperature were active. Another lot of larvae 

 from the same source was heated in the same maimer, the temperature 

 rising from 20° to 51° in 21 minutes, and then dropping in 6 minutes to 

 45.8°. One hundred and thirty-nine larvae were then examined at room 

 temperature, and 65 of them were found to be inactive. Of the 74 active 

 larvae, all but 2 were sluggish. A third lot of larvae from the same source 

 was heated in the same manner from 24° to 50° in 12 minutes, and then 

 cooled to 46° in 6 minutes. Out of 159 examined, 18 were inactive. 

 Some of the 141 active larvae were sluggish. 



Experiment 3 (May 16, 1914). — Decapsuled larvae, isolated by artifi- 

 cial digestion from a mixture of meat from two trichinous rats, were 

 heated in a beaker of constantly stirred water over a water bath. The 

 temperature was raised from 23° to 48.4° C. in 8 minutes and held at 

 48.4° I minute. The beaker was then allowed to cool. One hundred and 

 ten larvae were examined on a warm stage. Thirty-five were inactive 

 and 75 active, mostly very lively. Another lot of larvae from the same 

 source was heated in the same manner from 22° to 51° in 10 minutes. 



