FEIGNING DEATH. 309 



For if this peculiar physiological condition is apt to occur 

 among insects and spiders — as it certainly occurs in an 

 animal belonging to the same class, tlie cray-fish — there 

 would be supplied to natural selection the material, as it 

 were, out of which to form this instinct. And if such were 

 the origin of the instinct, we may presume that its develop- 

 ment to its present state of perfection would most likely be 

 continued along the same lines — natural selection always 

 improving the kataplectic susceptibility, so as to make the 

 state occur with great suddenness under the influence of a 

 certain class of stimuli, and to prevent it from lasting for an 

 unnecessary time after such stimuli had ceased to operate. 

 Thus we might arrive at the existing state of things, in such 

 an animal as a ^^'ood-louse or death-watch, which fall into a 

 kataplectic state immediately on being alarmed (when, on the 

 present hypothesis, they are quite insensitive to pain), but 

 quickly recover as soon as the source of alarming stimula- 

 tion is removed.* 



We have here, then, a rather interesting speculation of a 

 not improbable kind as to the strange, and, so to speak, far-o 

 peculiarities of organization on which natural selection may 

 seize for the developing of a beneficial instinct. But I desire 

 it to be particularly noted that I only adduce this specula- 

 tion, as it were, parenthetically. I think with Preyer that 

 the shamming dead of insects is a phenomenon in which the 

 principles of hypnotism are probably concerned. But if so, 

 I regard these principles only as furnishing the materials oul 

 of which natural selection has constructed this particular 

 instinct. Therefore, whether or not these principles are really 

 concerned in the phenomenon, is only a side C[uestion ; the im-[ 

 portant consideration for us is, that the instinct, whether or 

 not developed from materials supplied by kataplexy, must 

 certainly have been developed by natural selection. ]\Ir. 

 Darwin's observations place this conclusion beyond the reach 



* An objection to tliis view may liere be disposed of : Duncan, " On 

 Instinct," after observing that spiders while slianiming dead. " will suffer 

 themselves to be pierced with pins and torn to pieces without discovering the 

 smallest signs of terror," adds that if the cause were, as often supposed, " a 

 kind of stupor occasioned by terror," the animal ought not so soon to recover 

 when the object of terror is removed. But as a matter of fact the " stupor " 

 does not pass off immediately upon the cessation of the stimulus ; it lasts as 

 long as the kataplectic state does in certain birds, such as the owl when hekl 

 on its back. 



