Aug. IS, I9I9 Effects of Heat on Trichince 203 



determine the effects of the heating upon the vitality of the parasites 

 they fed the meat to rabbits, which were examined for trichinae 15 to 30 

 days after feeding. 



Perroncito (7) records observations on the behavior of the larvae under 

 the influence of high temperatures and draws the conclusion that a tem- 

 perature of 48° to 50° C. is sufficient to kill the parasites. He placed 

 decapsuled larvae as well as encysted larvae in salt solution and examined 

 them on a warm stage. He observ^ed that as the temperature increased 

 the larvae became more active, but that at 45° C. their activities ceased. 

 If the temperature was lowered they resumed their activities. If the 

 temperature was raised to 48° or 50° C. they became completely inactive 

 and remained so even when the temperature was lowered. 



Vallin (ij) records a series of experiments on the effects of heat on 

 trichinae. He heated small pieces of trichinous meat in tubes containing 

 water, placed the tubes on a sand bath, and read the temperatures on a 

 thermometer with which each tube was provided. He found that a 

 20-minutes' exposure to a temperature of 60° C. resulted in a complete 

 destruction of the vitality of the larvae. He fed the heated meat to two 

 rabbits and four guinea pigs and failed to infect them. Vallin states 

 that temperatures below 60° C. are uncertain in their effects, since after 

 heating meat to 56° C. he succeeded in infecting with it one guinea pig, 

 although two rabbits to which the meat was fed escaped infection. 

 He tried temperatures lower than 56° C. and found them ineffective. 



Leuckart (6) states that Trichinella spiralis does not perish until it is 

 acted on by a temperature ranging betw^een 62° and 69" C. 



Piana {8) concluded as a result of certain experiments that a temper- 

 ature of 56° C. is fatal to the larvae of Trichinella spiralis. 



Ransom (jo, p. 159) states: 



With reference to the effects of high temperatures upon the vitality of trichinae, 

 various statements are found in the literature which seem to have for the most part 

 rather imperfect experimental evidence as a basis. From a rather small series of 

 experiments conducted within the last two years, I have found that encysted trichinae 

 regularly die when exposed for a short time to a temperature somewhere between 

 53° and 55° C. 



The earlier of these experiments supplied the data upon which w^as 

 based the following statement (9): "The results already obtained in the 

 investigations . . . show that the parasites die after a brief exposure 

 to a temperature between 53° and 55° C." 



Winn {14) records a series of experiments in which trichinous meat 

 was heated to certain temperatures, maintained at those temperatures 

 for 15 minutes, and then fed to experimental animals. The effect of 

 the heat was judged by the degree of infection as compared with that of 

 animals fed on similar quantities of meat w^hich were unheated. Winn 

 found that temperatures below 53° C. produce no apparent effect upon 



