THE DARWINIAN THEORY OF INSTINCT. 599 



Some of these insects he then killed, and he found that in no case did 

 the attitude in which they feigned death resemble the attitude in which 

 they really died. Consequently we must conclude that all the instinct 

 amounts to is that of remaining motionless, and therefore inconspicu- 

 ous, in the presence of danger ; and there is no more difficulty in 

 understanding how such an instinct as this should be developed by 

 natural selection in an animal which has no great powers of locomotion 

 than there is in understanding how the instinct to run away from dan- 

 ger should be developed in another animal with powers of rapid loco- 

 motion. The case, however, is not, I think, quite so easy to understand 

 in the feigning death of higher animals. From the evidence which I 

 have I find it almost impossible to doubt that certain birds, foxes, 

 wolves, and monkeys, not to mention some other and more doubtful 

 cases, exhibit the peculiarity of appearing dead when captured by man. 

 As all these animals are highly locomotive, we can not here attribute 

 the fact to protective causes. Moreover, in these animals this behavior 

 is not truly instinctive, inasmuch as it is not presented by all or even 

 most individuals. As yet, however, observation of the facts is insuffi- 

 cient to furnish any data as to their explanation, although I may remark 

 that possibly they may be due to the occurrence of the mesmeric or 

 hypnotic state, which we know from recent researches may be induced 

 in animals under the influence of forcible manipulation. 



The instinct of feigning injury by certain birds presents a peculiar 

 difficulty. As we all know, partridges, ducks, and plovers, when they 

 have a brood of young ones, and are alarmed by the approach of a 

 carnivorous quadruped, such as a dog, will pretend to be wounded, 

 flapping along the ground with an apparently broken wing in order 

 to induce the four-footed enemy to follow, and thus to give time for 

 the young brood to disperse and hide themselves. The difficulty here, 

 of course, is to understand how the birds can have acquired the idea 

 of pretending to have a broken wing, for the occasions must be very 

 rare on which any bird has seen a companion thus wounded followed 

 by a carnivorous quadruped ; and even if such observations on their 

 part were of frequent occurrence, it would be difficult to accredit the 

 animals with so high a degree of reasoning power as would be re- 

 quired for them intentionally to imitate such movements. When I 

 consulted Mr. Darwin with reference to this difficulty, he gave me a 

 provisional hypothesis by which it appeared to him that it might be 

 met. He said that any one might observe, when a hen has a brood 

 of young chickens and is threatened by a dog, that she will alternately 

 rush at the dog and back again to the chickens. Now, if we could 

 suppose that under these circumstances the mother-bird is sufficiently 

 intelligent to observe that, when she runs away from the dog, she is 

 followed by the dog, it is not impossible that the maternal instinct 

 might induce her to run away from a bi'ood in order to lead the dog 

 away from it. If this happened in any cases, natural selection would 



