210 yoiirnal of Comparative Neurology and Psychology. 



The shock-efFects of decapitation in Ranatra are comparatively 

 very slight. I have kept specimens for several days after this 

 operation and probably could have kept them much longer by 

 observing the proper precautions. In one set of experiments 

 fifteen Ranatras were decapitated with a pair of fine scissors. 

 When liberated most of the specimens were able to walk about 

 in an apparently normal manner soon after the operation. They 

 were much more restless than normal individuals and moved 

 about ceaselessly without any apparent external cause. Those 

 that I took up in my hand soon after decapitation either did not 

 feign death at all or feigned for only a few seconds. Many of 

 them when picked up would spread' apart the anterior legs and 

 move them up and down producing their characteristic squeaking 

 sound* in the usual way. When placed on their backs they would 

 rig-ht themselves as readily as the normal insects. After five hours 

 of restless perambulation all of the individuals operated upon 

 became quiet. Thev proved, however, to be extraordinarily 

 sensitive to stimuli. Even the disturbance of gently raising the 

 CQver of the glass dish in which they were confined caused most 

 of the Ranatras to begin moving around. The others were 

 roused to activity when a very slight breath of air was blown upon 

 them. For over four hours they walked about and clambered 

 over each other in the most restless manner. Should one settle 

 down to rest it would soon be set going again by another individual 

 wandering over it. The specimens paid no attention to the 

 light of the window near which they were placed, and subsequent 

 experiments showed that they were insensitive to much stronger 

 illumination. Ten hours after decapitation all of the specimens 

 were picked up, stroked gently, and then thrown down upon the 

 table. Most of the specimens feigned death in the characteristic 

 manner, but only for a few seconds. Some, however, continued 

 to feign for three or four minutes. In this feint they show the 

 same state of tetanus as normal individuals do under the same 

 conditions. Specimens feigning with the legs drawn up dorsally 

 were found to lie in an inverted position supported only by the 

 tips of the outstretched legs and the caudal end of the body. 

 This certainly gives evidence of a considerable degree of muscular 

 rigidity. When seized by the tips of the anterior legs and held 

 out horizontally with the ventral side upward they maintain them- 

 selves in a perfectly rigid attitude for several seconds, and then 



