REPORT OF THE SOCIETY 15 



and that the number of feints produced by repeated stimulations is not 

 indefinite. After a period of rest the insect recovers to a certain extent 

 and reacts to shock. 



When the insect in the death feint is mutilated by the removal of legs 

 and antennae it still remains quiescent, and on recovery can be made to 

 feint again. On the other hand removal of the tip of the abdomen or 

 division of the body in the thorax or between the thorax and the abdomen 

 brings the insect out of the feint. When insects in feint are placed on iron 

 plates lightly warmed they become active, and the feint is not produced 

 by dropping the insect on a hot plate, but is readily produced when it is 

 dropped on a plate slightly above the temperature of the room. 



Feinting is readily induced at a temperature of 11°C. and its duration 

 is much longer. Cold alone, without shock, produces death feint. 



When insects in feint were introduced into vapor of chloroform, diffi- 

 culty was found in getting them to feint again, but in vapor of ether a suc- 

 cession of feints can be induced, but not so many as in normal air. 



Mr. DuPorte is inclined to the view that the death-feint reactions 

 are largely thigmotactic, or responses due to the stimulus of touch. It is 

 probable, he says, that the reaction is often complex, and involves the action 

 of another stimulus besides touch. 



It may be noted that the death-feigning instinct is not always advantag- 

 eous to the insect, and can scarcely be considered as one evolved by natural 

 selection for the benefit of the species. 



Bohn is of the opinion that this instinct in insects is an exaggeration 

 of the "differential sensitiveness" of simpler animals when a reaction is 

 shown to sudden and marked changes in the strength of the stimulus. A 

 shadow passing across a worm will cause it to contract for example. 



Intelligence. 



It is, however, among the higher and more specialised insects that in- 

 telligent actions can be observed superadded, as it were, to instinctive 

 actions. Bees, wasps and ants have been carefully studied and observed 

 for a long time. 



Are these intelligent actions modifications of instincts due to their 

 flexibility or variability, or have they originated apart from instinct? 

 Does experience influence instinctive actions? 



Professor Jenning's experiments with unicellular animals — the In- 

 fusorians — show that their behaviour cannot be explained as entirely due 



