Holmes, Deaih-feigmng in Ranatra. 207 



specimens were exposed to a temperature of 34° C. The dura- 

 tion of the feints was as follows : 



Specimens Kept at 22° C. Specimens Kept at 34° C. 



16 



30 

 34 

 40 



49 21 



83 34 



88 39 



41 



Average 50.57 minutes. Average 22.75 minutes. 



The experiments show that heat diminishes and cold increases 

 the duration of the death feint to a very marked degree. This 

 result is similar to that which Fabre obtained in experimenting 

 on the Buprestid beetle, Capnodis tenebrionis Lin. Ordinarily 

 this beetle feigns death for less than an hour. Exposed to cold, 

 its feint continued for over five hours. In Scarites, on the other 

 hand, Fabre^ found that a slight decrease of temperature caused 

 the death femt to become shorter, a result not improbably due 

 to the shock effect of the trans't.on. 



Ranatras transferred from the ordinary temperature of the 

 room to a temperature of from o° C. to 4° C. often come out of 

 the death feint almost as soon as they touch the cold bottom of 

 the glass dish. The cold acts as a sudden stimulus to them and 

 they react much as if they were laid against a hot surface. If 

 they are kept longer at this temperature they move about very 

 sluggishly as if benumbed, and finally settle down to a compara- 

 tively quiet state. This condition is, in great measure no doubt, 

 due to cold rigor, and in the specimens which are not aroused by 

 the sudden chill it is not possible to determine when the death 

 feint terminates, since the insects lie quiet in both of these con- 

 ditions. Specimens which I had kept for some tune in water at 

 10° C. and then transferred to a glass dish at a temperature of 

 4° C. continued to feign death without interruption. The transi- 

 tion in this case was not so great and the specimens were not 

 subjected to the sudden shock which they received in the former 



'Souvenirs Entomologiques. 7me. Ser., p. 14. 



