DEATH FEIGNING REACTIONS IN TYCHIUS PICIROSTRIS 141 



the femora and the tarsi bent backwards. The rostrum is almost 

 perpendicular to the body and the antennae are folded together 

 behind the rostrum. 



Often the insect becomes quiescent on being stimulated, with- 

 out assuming the attitude described in the foregoing paragraph. 

 In such cases it may remain perfectly still with the legs out- 

 stretched or partially and asymetrically flexed. This attitude 

 I have termed the partial feint and it will thus be referred to 

 when necessary to distinguish it from the typical feint. Some- 

 times the insect when stimulated assumes the typical death feign- 

 ing attitude, but after a while it slowly relaxes its legs without 

 becoming active. Usually but not invariably the partial feint is 

 manifested after the insect has been repeatedly stimulated. It is 

 therefore probable that the failure to flex the legs is due to 

 muscular fatigue. 



Variability of the Feigning Response. The feigning response to 

 tactual or shock stimuli is not stereotyped as there exists a 

 considerable range of variability in the duration of the feint, 

 not only in the different individuals but in the same individual 

 in successive feints. In some cases too, as stated above, I 

 found it impossible to evoke the feigning response by any means. 

 The reaction of mutilated specimens was also not constant owing 

 no doubt to slight differences in the sensitiveness of the nervous 

 system which would influence the intensity of the shock effects 

 of mutilation. While any general statement made is based on 

 the results of the reaction of the majority of individuals, the 

 number failing to give the typical response was in some cases 

 considerable, and for this reason special attention is called to 

 the fact here. 



As to the exact cause of this variability I am unable to give 

 a positive explanation. Probably, however, it is not wholly 

 due to the inherent individuality of the specimens but partly 

 to the varying "experiences" of the individuals. If the insects 

 had been kept under the same conditions from the time of their 

 eclosion it is probable that the reactions would be more nearly 

 uniform, or where a wide variability exists there would be 

 an evident explanation. 



Duration of the Death Feint. The duration of the feint at 

 room temperature is usually very short, the insect recovering 

 almost invariably before the expiration of a minute. The 



