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



they would often remain in this quiet state for hours at a time 

 with their muscles perfectly lax. On account of the impos- 

 sibility of being certain just when the death feint ceases in every 

 case, it was decided to consider the time when the muscles of 

 the limbs became relaxed as the termination of the feints, al- 

 though in reality, the durations of the feints in each case were 

 somewhat longer. As soon as the muscles of the legs became 

 relaxed, the time was recorded, the individual being then in- 

 duced to feign death again. This was repeated until the aquatic 

 bugs would feign no longer. The experiment was begun at 

 8 A. M. and at 2.30 p. m. the last specimen refused to feign. Here 

 as with Belostoma, it was found that the durations of the 

 death feints decrease the oftener the insects are made to repeat 

 the performance. 



When the last three Nepas refused to feign, they were dipped 

 into water, which was at the temperature of the room, and 

 then they could be readily put into the feint again. In this 

 way, by dipping the bugs into the water whenever they refused 

 to feign, we succeeded in making them feign until four o'clock, 

 when the experiment was discontinued. Undoubtedly they 

 would have feigned longer had we continued the experiment. 



IV. THE EFFECT OF DRYNESS AND MOISTURE ON THE DURATION 

 OF THE DEATH FEINT. 



9. The effect of dryness on the death feint: In order to throw 

 some light on the problems suggested in connection wdth the 

 previous experiments with Belostoma, a number of experiments 

 were performed to determine the effect of dryness upon the 

 duration of the death feint. Fifteen Belostomas were taken out 

 of the water at 19° C. and exposed for one and a half hours to 

 the temperature of the atmosphere at 21° to 22° C. so that their 

 bodies might dry. It may be of interest to note here, that two 

 specimens at the end of this time made eager efforts to escape 

 by flying against the sides of the dish in which they were con- 

 fined. The following figures indicate the averages of the first 

 five successive death feints of each insect: .9, .9, 1.5, 1.7, 4.3, 

 4.5, 4.5, 7.2, 7.3, 7.8, 8.3, 10.2, 12.4, 12.5 and 18.2 minutes. The 

 average of these averages, or the total average, is 6.8 minutes. 



In the experiment under table II, the difference in temper- 

 ature of the water and the atmosphere was identical with the 



