140 THE ZOOLOGIST. 



antics) which immediately precedes the rolling, and which, also, 

 cannot properly be separated from it. All this set of actions 

 must be looked upon as so many parts of one and the same 

 whole thing, and to explain such whole thing we must call in 

 some cause which will equally account for all its parts. The 

 deliberate intention of making a nest will not do this, for many 

 of the actions noted do not in the least further such a plan. On 

 the other hand, sexual excitation may just as well produce rolling 

 on the ground (as indeed it does in some other birds*), and per- 

 haps, even, pecking round about on it, as it may the set, stiff run, 

 and those other peculiar movements. And if some of many move- 

 ments, the cause of all of which is sexual, should be of such a nature 

 that out of them good might accrue to the species, why should 

 not natural selection seize hold upon, increase, and gradually shape 

 them, making them, at last (through the individual memory), in- 

 telligent and purposive, since, by becoming so, their utility might 

 be largely increased, and proceed at a much quicker rate ? I believe 

 that in these actions of the Peewit — commencing immediately after 

 the excitation of pairing, with a peculiar run (which, or some- 

 thing similar to which, may be observed in various birds), and 

 going on, without pause or break, to other motions having the 

 same plain sexual stamp upon them, though some may, in their 

 effects, be serviceable — we see this process actually at work, 

 and I believe, also, that in the nest-building of species compara- 

 tively advanced in the art we may still see traces of its early 

 sexual or ecstatic origin. I have been, for instance, extremely 

 struck with the movements of a hen Blackbird upon the nest 

 that she was in course of constructing. I have not my notes at 

 hand, but these movements appeared to me to partake largely of 

 an ecstatic — one might almost say a beatific — nature, so that there 

 was a large margin of energy over and above the actual business 

 of building, to be accounted for. I was not in the least ex- 

 pecting to see this, and I can, perhaps, best estimate the extent 

 of the thing by recalling how it surprised and struck me. The 

 wings were half-spread out, and would, I think, have drooped, t 

 had not the edge of the nest supported them, and I particularly 



:;: Most notably in the Ostrich. 



f The drooping of the half-spread wings is very characteristic of sexual 

 excitement in birds. 



