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



pair of forceps, violent efforts were made to rub oft" the source 

 of stimulation with the tibia and tarsus of either one or both 

 hind legs. On pinching the posterior end of the body more to 

 the right side, the right leg made an eager effort to rub the 

 stimulated region, when more to the left side, the left leg was 

 used. Sometimes, however, both legs were used to rub the end 

 of the abdomen both on the dorsal and ventral surfaces. 



The swimming reflex can often be elicited with headless 

 Belostomas by simply throwing them into water. In one set of 

 experiments, sixteen indi\'iduals were decapitated while they 

 were lying on their backs in the inert condition. When the 

 cut was made, all of the bugs came out of the immovable state; 

 immediately after the operation, most of the insects could be 

 induced to assume the usual death-feigning posture, but they 

 maintained this condition for less than one minute. After they 

 were exposed to the atmosphere for half an hour, so as to enable 

 their wounds to heal somewhat, the insects were all thrown into 

 the water in which they had been swimming just before the head 

 was severed from the body, when it was found that thirteen 

 of the sixteen specimens swam about actively and in an appar- 

 ently normal manner. 



A beautiful example of a reflex act was observed in Belostoma 

 and Nepa. If decapitated Nepas, that had their front legs 

 extended, were touched lightly with a needle on the groove 

 of the femur or the inner surface of the tibia or tarsus, the tibia 

 and tarsus would invariably quickly close upon the femur. 

 If the leg was touched lightly on the outer, upper or lower sur- 

 face, the reaction was usually not given. Within three minutes 

 this reaction was given one hundred times, the needle being 

 applied alternately to the femur of each front leg and withdrawn 

 from the insect's grasp. As soon as the needle is withdrawn, the 

 tarsus and tibia are usually extended again. Although this reac- 

 tion is given by normal Nepas, it is not so invariably obtained 

 with these, owing jjrobably to the inhibitory action of the brain. 



Nepas, when stimulated upon the ventral surface of the ab- 

 domen about five minutes after decapitation took place, would 

 assume the rigid state of the legs, a condition which is so char- 

 acteristic of the death feint of normal individuals, but they 

 would maintain this state only for a few seconds. After the 

 lapse of five hours, some of the specimens, when stimulated, 



