460 THE ZOOLOGIST. 



necessarily, have been the desire to shelter and conceal the eggs. 

 It is possible that both that and the idea of doing so were de- 

 veloped after, and by reason of the nest itself, which, in its early 

 stages, may have been due to other and widely different causes. 

 Eggs and young must, of necessity, be preceded by sexual inter- 

 course, and in the case of the Crested — probably of all the 

 Grebes — it seems likely that such intercourse takes place on the 

 nest alone. With the vast majority of birds, however, this is 

 quite otherwise. Pairing on the nest, if it takes place at all (I 

 have observed it in the case of the Eook, which again brings us 

 nearer to the Bower-birds), does so probably as an exception, nor 

 is it easy to see why this should ever have been otherwise. But (if 

 I may be allowed to sketch my theory first, and give the facts on 

 which I found it afterwards) let us assume two things, neither 

 of which, perhaps, is highly improbable — viz. : first, that the 

 primaeval bird, or birds, made no nest; and, secondly, that the 

 first eggs were laid on the ground. Supposing, then, that a male 

 ground-laying bird that makes no nest indulges during the season 

 of love, till shortly before the actual laying of the eggs, in all 

 sorts of strange frenzied movements upon the ground, and that 

 these movements tend to become localized and concentrated in 

 some particular spot or spots in which — or one of which — the 

 . female, as sexually attracted thereto, ultimately lays her eggs, 

 have we not here the nucleus, or, at any rate, the potentiality, of 

 the future nest ? And where — before the eggs were laid — would 

 pairing have been so likely to have taken place as in one of these 

 very spots — these vortexes, so to speak, of the sexual whirlwind ? 

 Can we not imagine a custom, gradually shaping itself out of this, 

 of laying the eggs in some place where pairing was habitually in- 

 dulged in, so that if such place afterwards became, in any true 

 sense, a nest, we would here have habitual pairing upon it ? 



Having got so far, let us now suppose that one chief form of 

 these frenzied movements alluded to, is a rolling upon or a buzz- 

 ing or spinning over the ground, by which means the bird so 

 acting produces a larger or smaller depression in it. If the eggs 

 are laid in such a depression, they are now laid in a nest, but 

 such nest will not have been produced with any idea of conceal- 

 ing the eggs or sheltering the young. It will be due to nervous 

 and non-purposive movements springing out of the violence of 



