222 THE ZOOLOGIST. 



those of irrational action, nor need they always, that I can see, 

 become instinctive through lapsing. As time went on, it can 

 hardly be questioned that, through individual memory, some 

 conception would have begun to arise in the minds of birds as to 

 the connection of the present building of the nest, for instance, 

 with the future use to which it was to be put, and this must 

 almost necessarily have passed, by degrees, into their having a 

 clear purpose in building it, which they would probably be quite 

 unable to distinguish from the strong instinct to do so, by which 

 they would really be swayed. When once this point had been 

 reached, the most intelligent birds, working, as one may say, 

 perceptively as well as instinctively, might, without introducing 

 any one great modification, have yet made many small improve- 

 ments, and as the slowly increasing sum of these began to give 

 them an advantage, this general superiority of intelligence, as 

 well as the special results of it, would have been selected 

 through the same agency, pari passu with any instinctive — that 

 is to say, non-intelligent — beneficial variation. Thus the two 

 forces would have become mingled in varying degrees, according 

 to the greater or less intelligence of the species (since the 

 general factor would be likely to be reflected in any particular 

 application of it) but with a preponderance more or less marked, 

 and always great, in favour of the latter. 



If the nest-building instinct has, in its origin, had nothing 

 to do with the " sexual frenzy," then it is certainly odd that the 

 picking up and letting fall, or laying down again, of objects 

 from the ground, or material from the nest, should, in some 

 birds, be a feature of the paroxysms to which I have given that 

 name, both some time, a little or just before, during and imme- 

 diately after coition. No act lies more at the very basis of the 

 instinct, is more absolutely essential to it than is this ; and, 

 moreover, occurring under these circumstances, it must be 

 deemed a peculiar one. Yet if we do not recognise the con- 

 nexion here suggested, we must see in it only a mere irrelevant 

 coincidence. Again, it is noticeable that some of the movements 

 by which birds — even such as are fairly advanced in the art — 

 build their nests have an odd sort of resemblance to essentially 

 sexual ones. The Peewit, during early spring, goes through 

 peculiar movements on the ground, as the result of which a 



