cuckoo-birds and cuckoo-bees should both alike assume a more or less terrifying aspect. The facts point to the conclusion that in both cases the appearance has been brought into existence by Nature for the purpose of inspiring fear and respect among the enemies of the comparatively defenceless cuckoos, rather than of intimidating their victims. The cuckoo's plumage resembles that of the dangerous sparrow-hawk more than that of the milder kestrel.

Although a good deal is known of the ordinary habits of the cuckoo, there are nevertheless some important points upon which little has been ascertained. Most Englishmen believe that the mother-cuckoo lays her eggs in the nests of other birds, and assigns the honors of incubation and rearing of offspring to the foster-parents. The truth is, as has already been mentioned, that she never lays her egg in any nest, but deposits it on the ground, an act which has often been observed. Instead of flying around with the egg in her mouth searching for a nest in which to put it, this strange mother evidently locates a satisfactory nest first, then lays the egg on the turf, and finally transfers it by means of her mouth to its resting-place.

Several well-authenticated instances are known of a cuckoo placing her egg in a newly-finished nest which at the time did not contain any eggs of the lawful owner, and there is abundant evidence to prove that the cuckoo occasionally removes an egg to make room for its own. A celebrated German authority (Dr. Rey) has repeatedly found that after the insertion of the stranger's egg the number of those of the foster parents is reduced by one or two. If the legitimate owners of the nest are at home when the cuckoo pays her call they strenuously resist the intruder, and sometimes with success, for the strange egg has occasionally been found abandoned or broken on the ground near the

nest.

Moreover, the discovery of numerous breast-feathers of the cuckoo, scattered around the desecrated home, is eloquent testimony to a valiant but probably vain defence.

In England there is a popular belief that the cuckoo's egg resembles in appearance the foster parent's, so as to escape detection. In many cases, it is true, there is a very decided likeness, both in color and in markings that is simply marvellous, and seems almost to demand deliberate choice by an artistically trained intelligence, or a power of producing any given color to order on seeing what was required. Both these suggestions are, of course, utterly absurd, and unworthy of serious consideration. It is, however, beyond contradiction that color-matching occurs sufficiently frequently to render mere coincidence an impossible explanation. It has been suggested that abnormal eggs are often wrongly attributed to cuckoos, but the texture and greater thickness of the shell will, as a rule, enable anybody to identify the cuckoo's egg in case of doubt; and if the egg, when taken, be at all far advanced in incubation, the young bird may be extracted without serious. injury to the egg-shell, and then the curious conformation of the cuckoo's foot, two toes in front and two behind, will at once settle the matter, as woodpeckers are the only other birds that possess feet identical with these. "Abnormal" eggs are not found with any frequency in the nests of birds other than those which are unquestionably patronised by the cuckoo, and as there is no reason why cuckoo favor should induce "abnormality," it is almost certain that the great majority of reputed cuckoos' eggs are such in fact. The range of color and of marking is quite extraordinary; some eggs are white with small black spots, others dull gray mottled with brown or red spots. Others, again, are perfectly blue, or blue with a few freckles.

This being so, it is evident that great possibilities are open to Mrs. Cuckoo in making a match. At the same time, it is not reasonable to credit her with conscious and deliberate action. Cuckoos' eggs have been found in the nests of about a hundred different species of birds, even in that of the little wren, and one wonders how a pair of tiny wrens can supply the voracious appetite of their big foster-child. The most commonly selected nests (in England) are those of the hedge-sparrow, robin, wagtail, reed-warbler, and tree-pipit. Colormatching is achieved with great frequency among the pipits, and it is noteworthy that the eggs of the pipits themselves are remarkably variable in coloring, so that more or less successful matching may possibly be merely an accident. On the continent of Europe, the butcher-bird, whose eggs are also very variable, is often honored with the cuckoo's attentions, and again the colormatching is, as a rule, excellent. Hedgesparrows' eggs are hardly ever imitated, and the cuckoo's egg is glaringly conspicuous among the pale-blue shells. Is it reasonable to suppose that birds whose eggs are, as a rule, accurately copied by the cuckoo are extremely particular and resent the addition of a strange egg to their own, while others are indifferent or perhaps stupid? We are in ignorance as to whether some birds turn out of their nests an egg differing in appearance from their own, while others do not. Moreover, nobody has yet ascertained whether the presence of the cuckoo's egg is the cause of nests being forsaken soon after completion and before any eggs have been laid. The sharp eyes of a hungry hawk would be very liable to detect a nest containing a few pale-blue eggs, as well as one with a very decided blue tint, and consequently the presence of the cuckoo's egg may sometimes be the direct cause of an attack upon a pair of small parent-birds. It is probable that

some birds are more tolerant than others. Mischievous persons have often interchanged eggs of different species in numbers of nests, working endless confusion in the avian nurseries, to the complete satisfaction, however, of the nurses. Domesticated "broody" chickens will, of course, "sit" upon anything resembling an egg. On the other hand, an English blackbird, to whom a thrush's egg had been given, deserted her nest at once, but the more tolerant thrush, with whom a fair exchange had been made, "sat" on, quite unconcerned, and hatched the blackbird with her own young. Again, a cuckoo's egg was one morning found in the unfinished nest of a linnet, which had been under observation while building. The suspicious linnet suspended operations for fully three days, and was thought to have forsaken her nest. The cuckoo's egg was then removed. Next day the linnet returned, finished her nest, and in due course laid her eggs.

The above-mentioned facts bring me to what I consider the important part of this article-the belief that there is at work some selective principle tending to bring the cuckoos' eggs in course of time into color correspondence with those of their dupes, at any rate in some species. It is significant that cuckoos' eggs found in the nests of wrens never simulate the appearance of the wren's egg; in the deep-domed nest, with its small, round entrance, all is dark, and the color of the egg of no importance, for the wren in all probability never sees even her own eggs, and as long as the cuckoo's egg is not exceptionally large, the wren remains ignorant of the intrusion. Instinct is at times literally blind, even the maternal instinct that one fondly hopes will do all that is best for the child. It is not improbable that the love of birds for their eggs is often blind. There comes a time in the breeding season when the instinct to "sit" is overpowering, and some

birds will sit upon anything, either their own egg, one made of earthenware, or that of a cuckoo. It is conceivable that an ill-matching egg might at the beginning of the egg-laying period of a fastidious foster-parent cause desertion or be rejected, while later on, when the "sitting" instinct is strong, an equally conspicuous egg might be tolerated. Successful simulations would then hatch out early, and have a better chance of dealing destruction to the unhatched eggs of the fosterers, or their weak, newly-hatched young; whereas, if the cuckoo's egg were hatched last of the batch, the young cuckoo might have. too heavy a task, and fail to get his necessary monopoly of supplies.

The size, especially the width, of the cuckoo's egg is an important consideration in its fate. A very wide egg would project above the rest of the eggs, and might cause discomfort to the sitting. bird. It is remarkable that while the eggs of such birds as have been examined vary far less in breadth than in length, the egg of the cuckoo is more variable in breadth than that of any other species, probably in accordance with the diverse sizes of the eggs of the various foster-parents. Perhaps the most striking feature is the extraordinary smallness of the cuckoo's egg. Although the bird itself is more than double the length of a house-sparrow, its egg is hardly larger than that of the one bird that so richly deserves extermination.

It has been suggested that there are races of cuckoos, one race having been evolved as the successful patron of one species of foster-parent, another of a different species. If this hypothesis is correct, we might expect that there would be some sign of kinship among the cuckoos' eggs found in wagtails' nests, and among those found in hedgesparrows', and so on. Using size as a test of blood-relation, it has been ascertained that differences do exist making

wren-cuckoos and hedge-sparrow-cuckoos into distinct sets, and in the case of the former the difference is notably such as to cause the egg, which is remarkably small even for a cuckoo's, to approximate more closely to the size of the wren's egg. Hence it is highly probable that there are certain races of cuckoos whose members being closely related lay eggs of somewhat similar dimensions, and confine their attentions each to its own particular variety of foster-parent. Individual birds, recognizable by some peculiarity of voice or plumage, are known to return with unerring accuracy to the same spot year after year, and it is not improbable that such of the young as survive the perils of migration will resort to the place where they were reared, and will inherit their mother's partiality for the nests of some one species of fosterer, and also more or less of her type and coloration of egg. The males, too, young and old, would be likely to return to their old haunts, and thus family groups of cuckoos would tend to segregate themselves.

But an ounce of fact is worth several pounds of theory. In the neighborhood of Leipzig (Germany) no less than sev-enty nests containing cuckoos' eggs were found in one season, and fifty-eight of these were red-backed shrikes'. (This is one of the "butcher-birds," notable for impaling insects and small birds upon thorns.) In any given locality, then, the majority of cuckoos may prefer some one particular species for foster-parent, and so the chances may be in favor of male and female individuals of like rearing and pedigree mating together. The isolation of race from race is not perfect, as is evident from the faulty matching of many eggs. This may perhaps be accounted for by occasional matings between birds of unlike foster-parentage, and the inheritance by their offspring of a mixture of preferences which cancel