I. INTRODUCTION. 



The study of the death feint of Belostoma flumineiim and 

 Nepa apiculata was undertaken at the suggestion of Prof. S. J. 

 Holmes, whose own researches on this instinct have added new 

 interest to this line of work. The principal points which we 

 have attempted to bring out in this paper are: 



(i) The duration of successive death feints. 



(2) The effect of dryness and moisture on the duration of 

 the death feint. 



(3) The effect of temperature on the duration of the death 

 feint. 



(4) The effect of light on the duration of the death feint. 



(5) The effect of mutilation on the death feint. 



(6) The origin and development of this instinct. 



(7) The psychic aspect of the death feint. 



II GENERAL CHARACTERISTICS OF THE DEATH FEINT. 



I. Death-feigning posture compared with naturally dead speci- 

 mens: It struck Darwin (4, p. 364) that it would be a rather 

 strange coincidence if insects, when feigning death, should 

 exactly simulate the attitude of really dead specimens. He 

 writes, " I carefully noted the simulated positions of seventeen 

 different kinds of insects (including an lulus. Spider, and Oniscus) 

 belonging to the most distinct genera, both poor and first-rate 

 shammers ; afterwards I procured naturally dead specimens of 

 some of these insects, others I killed with camphor by an easy, 

 slow death ; the result was that in no one instance was the attitude 

 exactly the same, and in several instances the attitude of the 

 feigners and of the really dead were as unlike as they possibly 

 could be." However, according to Kirby and Spence (16, p. 448) 

 "the common dung-chafer {Geotrupes stercorarius) when touched, 

 or in fear, sets out its legs as stiff as if they were made of iron- 

 wire — which is their posture when dead — and remaining perfectly 

 motionless, thus deceives the rooks which prey upon them." 



Although the death-feigning postures of Belostoma are very 

 characteristic, the simulated positions are quite different from 



