364 MENTAL EVOLUTION IN ANIMALS. 



ous in this respect. We have amongst them a most perfect 

 seiies, even within the same genus (as I have observed in 

 Curculio and Chrysomela), from species which feign only for 

 a second and sometimes imperfectly, still moving their 

 antennae (as with some Histers), and which will not feign a 

 second time however much irritated, to other species which, 

 according to De Geer, may be cruelly roasted at a slow fire, 

 without the slightest movement — to others, again, which will 

 long remain motionless as much as twenty-three minutes, as I 

 find with Chrysomela spartii. Some individuals of the same 

 species of Ptinus assumed a different position from that of 

 others. Now it will not be disputed that the manner and dura- 

 tion of the feint is useful to each species, according to the kind 

 of danger which it has to escape ; therefore there is no more 

 real difficulty in its acquirement, through natural selection, 

 of this hereditary attitude than of any other. Nevertheless, 

 it struck me as a strange coincidence that the insects should 

 thus have come to exactly simulate the state which they took 

 when dead. Hence 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. 



Nidification and Habitation. — We come now to more 

 complex instincts. The nests of Birds have been carefully 

 attended to, at least in Europe and the United States ; so 

 that we have a good and rare opportunity of seeing whether 

 there is any variation in an important instinct, and we shall 

 find that this is the case. We shall further find that favour- 

 able opportunities and intelligence sometimes slightly modify 

 the constructive instinct. In the nests of birds, also, we 

 have an unusually perfect series, from those which build 

 none, but lay on the bare ground, to others which make a 

 most imperfect and simple nest, to others more perfect, and 



and closed eyes ; if further disturbed, it buried itself quickly in the sand. If 

 the Hare had been a small insignificant animal, and if she had closed her eyes 

 ■when on her form, should we not perhaps have said that she was feigning 

 death? In regard to Insects, see Kirby and Spence, Introduction to Ento- 

 mology, vol. ii, p. 234. 



