226 MENTAL EVOLUTION IN ANIMALS. 



But the influence of this faculty in the formation of 

 instinct proceeds further than we have yet noted. For 

 among the more intelligent animals it is played upon for this 

 very purpose by the animals themselves ; the parents of each 

 successive generation intentionally educate their young in 

 the performance of quasi-instinctive actions. Thus, for 

 instance, old hawks purposely educate the instinctive facul- 

 ties of their young, so as more quickly to bring these instincts 

 into a state of perfection. For the manner in wliich hawks 

 swoop upon their prey must certainly be regarded as instinc- 

 tive ; yet La Malle observed,* and the observation was after- 

 wards corroborated by Brehm,t that the old birds perfected 

 the natural instincts of their young ones in teaching them 

 "dexterity, as well as judgment of distances, by first dropping 

 through the air dead mice and sparrows, which the young 

 generally failed to catch, and then bringing them live birds 

 and letting them loose."t 



And analogous facts are to be observed in the case of old 

 birds teaching the young ones to fly. We have already seen 

 that Mr. Spalding proved such teaching to be unnecessary in 

 the sense of not being required to develop the power of flight. 

 This is instinctive, so that the young bird, whether or not 

 instructed by its parents, would fly. Yet the instruction 

 must be of some use, as in some species, at any rate, it is 



the natural nest, and then observe whether when adult these birds will 

 instinctively build the nest characteristic of their species. Now I find 

 among Mr. Darwin's MSS a letter to him from Mr. Weir, which seems to set 

 any such question at rest. Writing under the date May, 1868, Mr. Weir 

 says as the result of a large experience of birds kept by him in aviaries : — 

 " The more I reflect on Mr. Wallace's theory that birds learn to mnke their 

 nests because they have been themselves reared in one, the less inclined do I 

 feel to agree with him." .He gives the following fact, which seems to be con- 

 clusive against this theory : — " It is usual with many Canary fanciers to take 

 out the nest constructed by the parent birds, and to place a felt nest in its 

 place, and when the young are hatched and old enough to be handled, to 

 place a second clean nest, also of felt, in the • ox, removing the other, and this 

 is done to avoid acari. But I never knew that canaries so reared failed to 

 make a nest when the breeding time arrived. I have on the other hand 

 marvelled to see how like a wild bird their nests are constructed. It is cus- 

 tomaiy to supply them with a small set of materials, such as moss and hair ; 

 they use the moss for the foundation, and line with the finer materials, just 

 as a wild goldfinch would do, although, making it in a box, the hair alone 

 would be sufficient for the purpose. I feel convinced nest building is a true 

 instinct." 



* Anns, de Sc. Nat., torn, xxii, p. 406. 



t jUaff. Nat. Eifit., vol. ii, p. 402. 



X Descent of Man, p. 73. 



