STUDY ON THE DEATH-FEIGNING OF BELOSTOMA 21 



This result agrees with Fabre's (6, pp. 23-4) work on the 

 Buprestid, Capnoides tenebrionis Lin. and Holmes's (12, pp. 

 207-8) investigation on Ranatra. 



14. The effect of a sudden change in temperature upon the 

 duration of the death feint: The duration of the death feint 

 decreases w^hen Belostoma is taken from water at a high tem- 

 perature and exposed to a low temperature of the atmosphere. 

 In one experiment six Belostomas were taken from water at 

 21° C. and caused to feign upon a blanket at the temperature 

 of the atmosphere at 9° C. The averages of the first ten successive 

 death feints of each individual were: .3, .7, .8, i, i, and 1.7 

 minutes ; the total average was .9 minutes. This experiment was 

 repeated with a half dozen different Belostomas taken from 

 water at 23° C. and exposed to the temperature of the atmos- 

 phere at 12° to i3°C. with somewhat similar results. 



With Nepa it was found that previous exposure to a high 

 temperature of the water and a transition to an atmosphere 

 considerably lower in temperature, decreases the duration of 

 the death feint. In the first set of experiments, eighteen speci- 

 mens, that had been kept in water at a temperature of 22° to 

 23° C. for six hours, w^ere caused to feign at a temperature of the 

 atmosphere at 11° to 12° C, while eighteen different individuals, 

 that had been kept in water at 11° to 12° C. for twelve hours, 

 were also made to feign at the same temperature of the atmos- 

 phere. The averages of the first death feint in each experiment 

 were as follows: 



Nepas exposed to 11° to 12° C. throughout experiment, average 19.6 



minutes. 

 Nepas kept in water at 22° to 23° C. for six hours, then caused to feign 



at a temperature of the atmosphere at 11° to 12° C, average 6.9 



minutes. 



In the second set of experiments, one lot of Nepas, that had 

 been kept in water at 23° C. for three hours, was caused to feign 

 at the temperature of the atmosphere at 12° to 13° C, while an- 

 other lot, that had been kept in water at 12° to 13° C. was also 

 made to feign at the same temperature of the atmosphere. The 

 averages 'of the first death feint in each experiment were as 

 folio w^s : 



Nepas exposed to 12° to 13° C. throughout experiment, average 22.6 



minutes. 

 Nepas kept in water at 23° C. for three hours, then caused to feign at a 



temperature of the atmosphere at 12° to 13° C, average 7.6 minutes. 



