Aug. IS, 1919 Effects of Heat on Trichince 207 



iological salt solution or Ringer's fluid; and this was heated to the 

 desired temperature on a water bath over an open flame, or in an incubator. 

 After being cooled, individuals were removed with a pipette to hollow 

 ground slides, or in some cases transferred to a Petri dish or shallow 

 stender dish and allowed to cool. They were then examined directly on a 

 warm stage, either on slides or in the dishes, in order to determine the 

 results of the experiment. 



BEHAVIOR OF DECAPSULED LARV^ WHEN HEATED 



When trichina larvae are heated on a warm stage their reactions may 

 be directly observed with the microscope. As the temperature rises 

 they begin to uncoil and become very active, their activity gradually 

 increasing. When the temperature has reached the neighborhood of 

 50° C. spasmodic contractions are commonly observed, and the larvae 

 twist themselves into various shapes. With a further rise of temperature 

 they grow sluggish and may become either uncoiled and inactive or else 

 tightly coiled and quiescent. After passing into this sluggish condition 

 they may again become lively if the temperature is lowered, but if sub- 

 jected to a sufhciently high temperature for a sufficient length of time 

 they do not recover when removed to a cool place. 



Decapsuled trichinae killed by heat usually become uncoiled and assume 

 a characteristic shape resembling the figure 6. If allowed to stand for 

 some time the protoplasm becomes dull, certain granulations appear, 

 and often the cell partitions in the gonads can no longer be distinguished. 

 Larvae in this condition are readily recognizable as dead. Sometimes, 

 however, larvae that have been subjected to heat may remain loosely 

 coiled and the protoplasm may not undergo any conspicuous changes. 

 From experience it has been learned that larvae in this condition are 

 usually dead. A generally satisfactory test of life is heat stimulation; 

 if still viable the larvae will usually uncoil and move. Even individuals 

 with a minimum amount of vitality will move the anterior or posterior 

 end very sluggishly. However, the most reliable test of life, or at least 

 of their viability from a practical standpoint, is feeding them to experi- 

 mental animals and thus determining their ability to reproduce; and 

 this has been done in some instances but not so regularly as in experi- 

 ments on encysted trichinae. 



DETAILS OF EXPERIMENTS 



Some experiments on the effects of heat on decapsuled trichinae were 

 made by the senior writer in 1913, 1914, and 1915, after which the work 

 was taken up by the junior writer and continued along the same general 

 lines. 



Experiment i (April 5 and 7, 191 3). — A decapsuled larva was sealed 

 under a cover glass in salt solution on a slide and heated to 54° C. on a 



