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



of naturally dead specimens. There is no- characteristic position 

 which Nepa assumes while simulating death, the attitude taken 

 depending mainly upon the position of the legs just previous 

 to the death feint. In Nepa it is sometimes impossible to dis- 

 tinguish with the eye alone, a death-feigning specimen from 

 one that is really dead. 



2. While in the death feint, these aquatic bugs labor under 

 an extreme muscular tension. A feigning Nepa may be taken 

 by any tibia or femur and held in a position so that the weight 

 of the entire body is born by the extensor muscle of a single 

 segment of but one leg. 



3. One of the most remarkable peculiarities of the death feint 

 in Nepa is the fact that it can be severely mutilated or dis- 

 membered without showing any apparent symptom of pain. In 

 Belostoma, however, severe mutilations can not be performed 

 without the specimen coming out of the death feint and making 

 violent efforts to escape. 



4. The first problem which we attempted to solve was to 

 determine how long successive death feints could be continued. 

 After one lot of Belostomas were put into thirty-eight death 

 feints on an average, they refused to feign. These specimens 

 could again be induced to feign death after placing them in 

 water a few minutes. This was repeated again and again until 

 finally the insects refused to feign longer, even after being immersed 

 in water. The average time that all of the Belostomas feigned 

 throughout all the series of successive death feints was eight 

 hours. The average duration of the first series of successive 

 death feints was five hours, thus making an increase of three 

 hours which the specimens feigned after being immersed in water 

 whenever they refused to assume the inert state. Similar results 

 were obtained with Nepa. 



5. The previous experiment suggested a number of problems: 

 (i) Why the reactions towards the end of this experiment should 

 be weaker; (2) why the duration of the death feint diminishes 

 with successive trials, and (3) the cause of the cessation of the 

 feint in each series of successive death feints. From our experi- 

 ments on the effect of dryness on the death feint, the explana- 

 tion of these problems cannot wholly be attributed to fatigue, 

 but must be ascribed, in part at least, to the drying of the body 

 when exposed to the atmosphere. 



