over their rivals before obtaining them. Thus, whilst the female sticklebacks are very pacific, their males are of war-*like humour, and engage in furious combats in their honour. In the same way the male salmon, whose lower jaw lengthens into a crook during the breeding season, are constantly fighting amongst each other.[1]
The higher we ascend in the animal kingdom the more frequent and more violent become two desires in the males—the desire of appearing beautiful, and that of driving away rivals. In South America, the males of the Analis cristellatus, a fissilingual saurian, have terrible battles in the breeding season, the vanquished habitually losing his tail, which is bitten off by the victor. An old observer also describes the amorous male alligator as "swollen to bursting, the head and tail raised, spinning round on the surface of the water, and appearing to assume the manner of an Indian chief relating his exploits."[2]
But it is particularly among birds that the sentiment, or rather the passion, of love breaks out with most force and even poetry. It is especially to birds that the celebrated Darwinian theory of sexual selection applies. It is difficult, indeed, not to attribute to this influence the production of the offensive and defensive arms, the armaments, the organs of song, the glands of odoriferous secretion of many male birds, also their courage, the warlike instinct of many of them, and lastly, the coquetry of the females. Let us listen to Audubon, as he relates the loves of the skylark:—"Each male is seen to advance with an imposing and measured step, swinging his tail, spreading it out to its full extent, then closing it again like a fan in the hands of a fine lady. Their brilliant notes are more melodious than ever; they repeat them oftener than usual as they rest on the branch or summit of some tall meadow reed. Woe to the rival who dares to enter the lists, or to the male who simply comes in sight of another male at this moment of veritable delirium: he is suddenly attacked, and, if he is the weaker, chased beyond the limits of the territory claimed by the first occupant. Sometimes several birds are seen engaged in these rude combats, which rarely last more than two or
