the bower or run of the Australian Bower-birds. Had these two Grebes paired or coquetted about the old nest whilst they were building the new one, here would have been, in fact, something very like the actual bower; and that a nest might come in time to be regularly made for this special purpose, and then used more generally, and also to be more and more ornamented and modified owing to general or special causes (with regard to which latter I would refer again to my previous remarks), should not seem very astonishing to any evolutionist.
Once let there be pairing on the nest—which I have seen in other instances—and the bower, as it appears to me, is no longer such a mystery.
Of course, I am aware how widely the bower often differs from the nest of the same bird, yet not more widely than does one nest, or even one bower, from another, or than a palace or other elaborate building differs from a savage dwelling, or even from a small house or cottage.
Differences in the site chosen for the nest and bower may offer a difficulty, but, if I mistake not, the principle of evolution has been accepted as overcoming greater difficulties than this. Birds, indeed, exhibit great adaptability in the placing of their nests.
It is true that in standard works of ornithology we are told that the "bowers" have nothing to do with the nests of the species making them, whilst, at the same time, complete ignorance as to their origin and meaning is confessed. If we know nothing about a thing, how do we know that it has nothing to do with some other thing? On the other hand, when we find a vast number of birds making a certain structure—the nest—which is an outcome and effect, with them, of the sexual instinct, and when we find also a few birds making, besides the regular nest, other structures of a more directly sexual character—as to which one has only to read the accounts, or to observe the actions, of the Satin Bower Birds in the Zoological Gardens—the prima facie likelihood would seem to be that there is, and not that there is not, a connection between the two instincts.
May 23rd.—First I will say that I forgot to note down yesterday that, after the birds had been building some little while,
