308 MENTAL EVOLUTION IN ANIMALS. 



wild animal on being captured may be sufficient to cause 

 actual death, and the researches of Professor Preyer on the 

 hypnotism of animals (conducted long after Couch's book was 

 published and having no special reference to the present 

 question), showed that fright is a strong predisposing cause 

 of " Kataplexy," or mesmeric sleep in animals. 



This allusion to Professor Preyer's researches leads me 

 next to remark that he ascribes the shamming dead of insects 

 to the exclusive influence of kataplexy. Having observed 

 the potency of this influence in producing analogous condi- 

 tions in the neuro-muscular systems of higher animals — even 

 as far down the series as the cray-fish, which were made to 

 stand upon their heads while in the hypnotic state — it was 

 perfectly logical in him to attribute the shamming dead of 

 insects to the same cause. And his reasoning might have 

 been greatly strengthened had he been aware of the import- 

 ant facts which had been observed by Mr. Darwin, and 

 which are now given in the Appendix. These facts, it will 

 be noted, are, that there is no species of spider or insect of 

 which it can be said that the attitude assumed when sham- 

 ming death at all closely resembles the one which the animal 

 assumes when really dead ; that in many cases this attitude 

 is very dissimilar ; and therefore that all " shamming dead " 

 amounts to in these animals is an instinct to remain motion- 

 less, and thus inconspicuous, in the presence of enemies. 

 And it is easy to see that this instinct may have been de- 

 veloped by natural selection without ever having been of an 

 intelligent nature — those individuals which were least in- 

 clined to run away from enemies being preserved rather 

 than those which rendered themselves conspicuous by move- 

 ment. 



That is to say, it is easy to see how the instinct may have 

 become developed by primary means ; for if it were of more 

 advantage to an animal when in danger to become motionless, 

 and therefore inconspicuous or unattractive to enemies, than 

 it would be to seek safety in flight, of course it is obvious 

 that in such cases natural selection would always have 

 operated in the direction of producing quiescence, no less 

 than in other cases it would have operated in the direction of 

 producing activity. Now, I think it is not at all improbable 

 that " kataplexy " may have been of much assistance in 

 originating, and possibly also in developing, this instinct. 



