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



with certainty just when the leg muscles became relaxed. The 

 severed anterior portion continued to feign from two to eleven 

 minutes and could readily be made to repeat the performance. 

 The posterior part, when stimulated, would react like the de- 

 capitated specimens by stiffening out the legs, the rigidity, 

 however, being lost soon after. In no case did the posterior 

 part even attempt to right itself; the anterior portion, on the 

 other hand, w^ould right itself very readily and pull itself for- 

 ward with the front legs, frequently falling over forward upon 

 its back while moving in this manner, but soon righting itself 

 again and continuing on its course. 



If, instead of cutting Nepa in two, the nerve cord is cut in 

 the same region as before through a small slit made on the 

 ventral surface of the body, the insect will live somewhat longer. 

 The part anterior to the cut may then be put in the death feint, 

 while the muscles of the posterior pairs of legs are perfectly lax. 



23. Reactions of Nepa with the body cut across the metathorax 

 behind the last ganglion: In one experiment ten Nepas, w^hile 

 in the death feint, w^ere cut in two across the metathorax just in 

 front of the hind legs. In this operation the insects were cut close 

 behind the last ganglion, which is situated towards the anterior 

 end of the metathorax. In nearly every instance did the anterior 

 portion continue to feign, remaining in the same inert position 

 for a period varying from two to nineteen minutes, the temper- 

 ature of the room being 18.5° to 19° C. The posterior part, 

 which contains no ganglion, remained perfectly quiet with the 

 hind legs very lax and did not respond to any stimulus, even 

 when a red hot needle was applied to the ventral surface of the 

 abdomen. 



From these mutilation experiments on Nepa, it is evident that 

 the severed part of the body retaining the brain will feign death 

 for a considerable length of time, the legs, when the body is 

 turned over and over laterally, assuming the characteristic 

 position taken by intact specimens that have been put into 

 the death feint in this way. The severed posterior part of the 

 body or the part lacking the brain will, if it contains a ganglion, 

 extend the legs out stiffly when the body is stimulated, but the 

 rigidity of the muscles will be maintained only for a short time. 



24. The effect of light on the severed parts of the body: The 

 severed parts of five Belostomas, which had been cut in twa 



