18 HENRY H. P. SEVERIN AND HARRY C. SEVERIN 



minutes longer, upon the surface film. In some individuals thus 

 experimented upon, we observed that when they arose to the 

 surface film and came out of the death feint, they would take 

 in a fresh supply of air almost immediately. It is evident, 

 thus, that the duration of the death feint diminishes when 

 Belostoma is caused to feign below the surface of the water . 



While Nepa will also feign death in water, it does so only 

 for a short time. In one experiment, nine specimens were taken 

 out of water, which was at a temperature of 17° C, and after 

 being put into the death feint in the usual manner, were again 

 placed into the same water. In every instance they continued 

 to feign, but only for a short time varying from forty seconds 

 to somewhat less than four minutes. The following figures are 

 the durations of the death feints in seconds of the nine speci- 

 mens: 40, 55, 60, 60, 65, 90, 170, 180 and 215. 



In a second experiment nine Nepas were made to feign without 

 taking them out of the water, which was at a temperature of 

 17° C, by merely touching them upon their backs two or three 

 times with a pencil. In every instance care was taken to keep 

 the insect entirely submerged. The durations of the death feint in 

 this case were : 50, 60, 70, 90, 90, 115, 130, 180 and 180 seconds. 



In both of these experiments, the first sign of Nepa coming 

 out of the death feint was a movement of the breathing tube. 

 The legs were then moved and, if the aquatic bug was on its 

 back, righting took place, after which the abdomen with its 

 breathing tube was raised so that the latter penetrated the 

 surface film. Some specimens were made to feign again and 

 again before they were permitted to reach the surface film 

 with their breathing tube, but soon all efforts to put these insects 

 into the death feint, without first permitting them to reach the 

 surface of the water with their breathing tube, failed. If these 

 individuals were allowed to take in air, however, they could 

 very readily be put into the death feint again. 



V. THE EFFECT OF TEMPERATURE ON THE DURATION OF 

 THE DEATH FEINT. 



12. The effect of a high temperature on the duration of the death 

 feint: The duration of the death feint diminishes if Belostoma 

 and Nepa are caused to feign in a high temperature. In one 

 experiment five Belostomas were taken out of water at 25° C. 



