after an interval of forty-eight hours, we found the young cuckoo alone in the nest, and both the young pipits lying down the bank, about ten inches from the margin of the nest, but quite lively after being warmed in the hand. They were replaced in the nest beside the cuckoo, which struggled about

until it got its back under one of them, when it climbed backwards directly up the open side of the nest, and hitched the pipit from its back on to the edge. It then stood quite upright on its legs, which were straddled wide apart, with the claws firmly fixed halfway down the inside of the nest, among the interlacing fibres of which the nest was woven, and, stretching its wings apart and backwards, it elbowed the pipit fairly over

the margin, so far that its struggles took it down the bank instead of back into the nest. As it was getting late, and the cuckoo did not immediately set to work on the other nestling, I replaced the ejected one and went home. On returning next day, both nestlings were found dead and cold, out of the nest. Here we have a definite account by an eye-witness, who sketched the young cuckoo, which was naked, blind, and could scarcely hold up its head. And her account, itself confirmatory of that given by Jenner in 1778, is confirmed by that of Dr. John Hancock,† who witnessed the ejection of a fledgling hedge-sparrow, which "was put over the edge of the nest exactly as illustrated by Mrs. Blackburn." The procedure is unquestionably instinctive.

The sounds uttered by young birds are sufficiently definite to be readily recognized and are susceptible of classification. In domestic chicks at least six notes may be distinguished. First the gentle "peeping " note, expressive of contentment. A further low note, a double sound, seems to indicate extreme satisfaction and pleasure. Very characteristic and distinct is the danger-note-a sound difficult to describe, but readily recognized. If a humble-bee, a black-beetle, a big worm, a lump of sugar--anything strange and largish-be thrown to the chicks, this danger-note is at once heard; and it serves to place others on the alert, though this is perhaps the outcome of experience. Then there is the cheeping sound, expressive apparently of a state of mild dissatisfaction with the present state of affairs. It generally ceases when one throws some grain, or even stands near them. Extreme dissatisfaction is marked by a sharper, shriller squeak, when one seizes them against their inclination. Lastly, there is the shrill cry of greater distress, when, for example, their swimming powers are subjected to critical examination. With pheasants a gentle, "peeping" note of contentment, a shriller cry of distress, and a danger-note, generically like, but specifically distinct from,

* "Birds from Moidart and Elsewhere," p. 107. Edinburgh: Douglas. † Transactions of Northumberland and Durham Natural History Society, vol. viii., p. 213.

that of the chick, are early differentiated. The complaining note of the partridge is uttered six or seven times in quick succession, followed by a pause. The note of the plover is high-pitched, and much like the familiar cry of the adult bird, to which it owes its popular name of "peewit." So, too, the guinea-fowl in down utters from the first notes quite characteristic of its kind, while its danger-note is not unlike that of the chick or pheasant. The piping of ducklings is comparatively monotonous, and there does not seem to be a definite danger-note. With moor-hen chicks, even on the first day, two notes are well-marked-a call-note, lower in pitch than that of the chick, and rather harsh and raucous, and a "tweet, tweet" of pleasure, something like the contented note of a canary. Later, five or six notes are differentiated, the most characteristic of which is the harsh "crek, crek," when the little bird is from any cause excited. It is uttered in a crouching attitude, with head thrown back and wings held outwards and forwards, waving to and fro in a very characteristic manner. That this has suggestive value for other moor-hen chicks is shown by its distinctly infectious effect; if one bird has cause to utter the note and strike the attitude others follow suit. While clearly instinctive in their mode of occurrence, while they seem to show well the co-operation of an internal emotional factor, their biological value seems to lie in their suggestive effect on other members of the brood. They form an elementary but sufficient social bond.

If these notes afford evidence of an incipient social factor, the instinct of pecking is distinctively individualistic. Chicks peck with considerable but not complete accuracy of aim at practically anything of suitable size at suitable distance; but it is through experience that they learn what to select for food and what to reject or leave untouched. Moving objects, however, are more readily pecked at than those which are still; and the instinctive response seems to be stimulated if one tap. on the ground near the object, or move it with a pencil, thus simulating the action of the hen. And this is even more

marked with pheasants and partridges.

Plovers seize small

worms with an avidity which looks like an inherited recognition of natural food. Pheasants and partridges also appear to be specially affected by worms, and when one of them seizes a worm for the first time, he shakes it and dashes it against the ground. Chicks, a week or ten days old, also seize a largish fly or bee with a dash, and maul it on the ground, throwing it on one side before again approaching it. And such birds seem to show an instinctive tendency to bolt with such treasures as caterpillars or small worms. Moor-hens cannot at first be induced to take food from the ground. It has to be held above them, whereupon they crouch down, with head and neck held back, opening their beaks more like the callow young of nursling birds; but they also strike upwards at the object-these modes of behaviour being, no doubt, correlated with the manner in which the mother moor-hen normally feeds her young from her beak during the early days of life. Callow fledglings, such as young jays, simply open their mouths, gaping widely to be fed. And many will respond in this way to such a note as a low whistle, as may readily be seen with swallows. But at a later age such birds show instinctive modes of reaction of a more complex type. A jay, for example, was offered a summer chafer or June bug, seized it at once in his bill, and tried to place his foot on it. Then he hopped down on to the floor of his cage, dropped the beetle, seized it again as it crawled off, and after two or three attempts swallowed it, tossing it back from the point of his bill into the throat. This was the first time he took food from the ground or swallowed it in this manner.

On the whole, there seems to be much inherited definiteness of co-ordination, and some tendency to respond in a definite manner to specific stimuli. That there should not be more differentiation in this respect than observation discloses is probably due to the fact that the parent birds afford, under natural conditions, so much guidance in the selection of food. Since the solitary wasp unerringly seizes its appropriate food, since it responds instinctively to specific stimuli, there would seem no reason why birds should not show similar instinctive

differentiation. But one must remember that in the case of the wasp there is no parental guidance; the insect is more completely dependent on instinct than is the bird to whose needs the hen assiduously ministers.

It is at first sight surprising that such birds as chicks and pheasants do not peck instinctively at still water. When a shallow vessel containing water was placed among some little chicks, several of them ran repeatedly through the water, but took no heed of it. Then, after about an hour, one of them standing in the vessel pecked at his toes, and at once lifted his head and drank freely with characteristic action. Another subsequently pecked at a bubble near the edge, and then he too drank. In fact, the best way of inducing them to drink is to scatter some grains of food in the tin; they peck at the grains, which catch their eye, and incidentally find the water, and the touch of water in the bill at once leads to the characteristic response and congenitally definite behaviour. That the sight of a still surface does not itself suffice to evoke this behaviour is probably again due to the fact that under nature the hen guides them and pecks at the water, when they follow her bill.

One fact which must be constantly borne in mind is that what is inherited is instinctive co-ordination, often related to a definite stimulus, not instinctive knowledge. A chick pecks at a grain when it is at a suitable distance, not because instinct provides him with the knowledge that this is something to be seized and tested, but because he cannot help doing so. He is so organized that this stimulus produces that result through an organic co-ordination that is independent of conscious knowledge or experience. How definite is the inherited coordination is shown by many observations. A young pheasant, only a few hours old, was taken from the incubator drawer, and held snugly while a piece of egg-yolk was moved before his eyes with the aid of fine forceps. He did not peck at it, but followed with movements of his head every motion of the object in a narrow circle. Simple as this action seems, it presents a striking example of co-ordinated movements