Evidence is not wanting that the evolution of pigment intensification and the consequent development of vividly coloured liveries, or the equivalent development of ornament, has been accompanied by an intensification of the reproductive instincts. For there can be no doubt but that the display of species which are conspicuous for their ornamentation is more animated than those of duller hues. As an argument in favour of this view the case of the display of the Great Crested Grebe may be cited, wherein each sex has developed both colour and ornament to a high degree, and are distinguishable only to the expert. The latest and the best exponent of the behaviour of this species under the spell of sexual exaltation is Mr. Julian Huxley, whose observations, in a condensed form, are now to be surveyed. The most conspicuous features in this bird are the great Elizabethan ruff of bright chestnut and dark Vandyke brown, and the long dark-brown tufts of feathers, or “ears,” which surmount the head. But the satin-like sheen of the white breast and the fore part of the neck and face add not a little to the general effect. These ornaments are worn only during the breeding season. So soon as the fires within begin to burn, the parade of this finery commences, and it would seem that a somewhat protracted dalliance takes place before any actual pairing. During the early phases of these performances much play is made with ruffs and “ears.” The courting pair will frequently face one another on the water, and go through a strange ceremony of head-shaking. To this is soon added a sort of ghost dance, wherein the male suddenly dives, leaving his mate swinging excitedly from side to side. In a moment or two, however, he appears, not suddenly, as usual, but arising gradually out of the water. He seems to “grow” out of the water. First his head appears, with ears and ruff extended, and beak pointed downwards; then his neck, and finally the body arises into view, till only the extreme tail end remains submerged, so that he looks more like a penguin than a grebe! All the while he is turning on his long axis, as it were, till he gradually displays before his mate the dazzling white sheen of his breast and neck, set off by the rich red chestnut and brown of his face and frills. A moment more and both subside into their normal attitude, shake their heads at one another, and then proceed to feed as if nothing had happened.