markably numerous, it follows, as a matter of simple arithmetical division, that the amount of sustenance supplied in the form of food-yolk by the parent to each egg is correspondingly small. Hence it comes about that the young insect, in many instances, issues from the eggshell at a very early stage of development. Its food stores being exhausted, it must henceforth procure its victuals by its own efforts. It must face the world alone, and generally without weapons or armor. Here, then, we have an almost unique combination of the conditions favorable to the moulding influence of natural selection. The plastic material is abundant, the pressure of the hand (or rather jaw) of the artificer is firm and sure. It is no mere chance accident that determines which one or two of the several hundred larvæ of a batch shall reach maturity. Death is the penalty for any shortcoming. Small wonder then that among all animals a high standard of efficiency is universal, and that among insects in particular we find the most striking instances of protective resemblance, of mimicry, of social organization, and of mechanical or chemical contrivance.

The puss moth affords a remarkable illustration of the results achieved by the rigorous selection to which we have just alluded. In early summer the eggs are laid upon the leaves of the poplar or willow-a few on this tree, a few on that. Nature has long since enforced the principle of not placing all in one basket. In a few weeks the young caterpillars emerge jet black, and easily mistaken for a dark, withered portion of a leaf. They are nevertheless provided with a pair of curious tails, from which can be everted two scarlet filaments. These conspicuous appendages are shot forth when the creature is alarmed, and are sufficient to deter certain enemies from pushing home the attack. With each

successive moult of the skin the appearance of the animal undergoes slight alterations, but throughout it is such as to-afford a good protection by concealment among the leaves and twigs of the food-plant.

By August the caterpillar is full grown, and is now some two inches in length, and curiously hump-backed. The body is for the most part green. But so large a mass, if uniformly green, would be conspicuous among the high lights and deeper shadows on the leaves. Accordingly, an undulating white stripe has been evolved upon each side to represent a strongly illuminated edge, and near it are various dark blotches and markings which give the effect of shadows. Although no very exact copy of a leaf is produced, yet the result is in very satisfactory harmony with the surrounding tints and patterns. Close behind the head there is a rather bright red band with two black spots upon it. When the creature is at rest and undisturbed this bit of gay color bears a very striking resemblance, both in size and tone, to certain bright red galls, which commonly form misshapen swellings upon the surface of poplar leaves. When danger threatens a further use is found for this conspicuous region of the body. The head is then suddenly drawn back, and, so to speak, telescoped into the front part of the body, so that the red belt forms the most advanced portion of the animal. The aspect now is that of the red and angry face of some much larger animal, whose two eyes are represented by the black spots mentioned above. In addition the scarlet caudal filaments (if they have not already been bitten off) are displayed to increase the terrifying appearance. But the resources of the soft-bodied caterpillar are not yet exhausted. If actually touched by an enemy it will spurt forth from a sac beneath its mouth a jet of formic acid which, should it reach the

eye or mouth, or other tender surface of the opponent, will cause intense smarting and pain, and probably a hasty retreat. It is one of the most marvellous things in nature that the strong acids and alkalis produced by various animals are tolerated by the tissues of the producers themselves. Yet, as we shall presently see, in this case a counterbalancing effect occurs in another region of the body.

The perils of early life being over, the caterpillar retires to the branches and climbs down the main stem to within a few feet of the ground. To diminish the risk of detection while-passing over the bark, the color of the animal assumes a decidedly darker tint. The object of this descent is that the older and more gnarled portion of the trunk may be reached, for it is amongst the irregularities of the bark that the cocoon is made and concealed. For this purpose fragments of bark are bitten off and incorporated with the silk which is spun out from the two silkglands. But here occurs a beautiful example of the economy of nature. The formic acid, which hitherto has been held in reserve as the last weapon of defence, is now put to a use entirely different. As the silk issues from the spinneret it is in a semi-liquid condition, and before it has time to solidify to a dry thread it is moistened with the acid, which keeps welling out from the sac in which it is stored. The effect of the acid is to make the thread swell and become viscid, so that it adheres to the bark and coalesces with the material already spun. So complete is the fusion that it is impossible to unravel the threads of the finished cocoon. fact, all filamentous structure completely disappears, and the whole wall of the cocoon becomes horny, like dried glue, and extremely hard. Chemically the method of the caterpillar is the same as that of the manufacturer of fish-glue.

In

Safe now from all external foes, the caterpillar throws off its skin and becomes a chrysalis. Thus it remains till the end of the following spring. The caterpillar has made good the deficiency of food with which the egg was provided, and the organism once again enters upon a period of apparent inactivity. It is as though the caterpillar, after a short interruption for the sake of procuring food, had crept back again into the eggshell. Nor are the processes that ensue within the cocoon very different from those within the egg. In both the tissues hurry towards their final structure, and fail to recapitulate, even in brief, the steps up which the species toiled in times gone by. During the chrysalis stage the muscles and many other organs of the caterpillar break down more or less into amorphous fatty masses, from which are elaborated direct the organs of the future moth.

But with the warmer weather of May there arises a fresh problem. How is the soft and downy moth to get out from the prison imposed upon it by its own ingenuity when a caterpillar? Preparation has been made during the period of rest. Within the body there develops in connection with the digestive organs, a special pouch, in which is stored a strong solution of caustic potash-an alkaline substance, which, as we have above suggested, may be set off against the acid produced at an earlier stage. When the moth is ready to emerge it cracks open the hard skin of the chrysalis, and struggles partly out of it. The combined lengths of the partly free moth and of the old husk then occupy the full extent of the cocoon cavity, and it becomes possible for the insect to press firmly with its head against the front, while the tail of the cast-off chrysalis case abuts against the hinder end of the cocoon. The caustic potash is now discharged from the mouth against the inner surface of the

cocoon, and quickly rots it. The tender fluffy head of the moth is still protected by the head and eyes of the chrysalis skin which separate from the rest, and remain as a shield over the parts which would otherwise be exposed to friction as the perfect insect bursts its way out of prison. Freedom is gained by the aid of a pair of sharp spikes, which project from the head beneath the protecting shield. These awls rasp and scrape away the material softened by the potash, while the shield is held firmly in place by means of hooks, which fit into "eyes" upon the head of the moth. At length the struggling creature frees itself and crawls a little The Pilot.

way up the stem. By means of its front legs it pulls off the shield which is now no longer required but rather is a mask obscuring the vision. In a few hours the wings have expanded and dried, and the moth is ready to fly away in search of a mate.

Correlated with the method adopted for passing through the winter, we find nearly all the most striking incidents of the life-history-the acid for the conversion of silk to glue, the potash for the destruction of the cocoon, the retention of the head and eyes of the chrysalis as a shield, and the awls for boring the hole that leads to light and liberty.

O. H. L.

thousands of readers will echo over the prevailing fashion of magazines of altering their cover from month to month. The Academy finds very annoying the difficulty of picking out one's favorite magazine on the bookstall or the library table, and observes that old acquaintance are apt to be forgot when they are continually changing their ap

pearance.

The three most read books in Germany during the past year were, according to the reports of the booksellers, three novels (and in the following order): Beyerlein, "Jena oder Sedan"; Heyking, "Briefe die ihn nicht erreichten"; and Frenssen, "Jörn Uhl." The authors, still novelists, who come next in popularity, are Clara Viebig. Thomas Mann and Georg von Ompteda. The German critics are rejoicing because for the first time for several years there are no foreigners among the most read novelists in Germany. In former years Zola, Tolstoi, and Sienkiewicz have taken high places.

The editor of "Who's Who in America" gives a humorous account in his preface of some of the difficulties which he experienced in getting his autobiographic material in manageable shape. For instance:

One gentleman of distinguished antebellum record "took his pen in hand," and wrote an installment of autobiography which brought him to the Mexican war in about eight thousand words, at the end of which he cheered the recipient with the assurance that the remainder would reach him in due time. It did: in about a dozen similar installments which arrived, with great regularity, in every Monday's morning mail until the story was told.

The ninth volume of Mr. Archer Butler Hulbert's series of monographs upon Historic Highways of America,-a series which no student of early American history can afford not to read,-is devoted to the waterways of western

expansion, and especially to the Ohio river and its tributaries. The Ohio river was one of the most important roads which immigration followed into the west, and Mr. Hulbert traces the history and development of this route from the voyages of Céloron and Father Bonnécamps in the middle of the eighteenth century, through the adventures of pioneer settlers who converged upon it from various historic land-roads, and the rough and romantic days of the keel-boatmen and bargemen, to the present time. There are several rare maps. The Arthur H. Clark Company.

A writer in The Athenæum, comparing and contrasting Zola and George Gissing, observes that the rise from Gissing's earlier work to "In the Year of Jubilee" and "The Whirlpool" is remarkable, and at a Bal

due distance "comparable to zac's rise out of those earlier and forgotten melodramatic tales of his to the heights of the 'Comédie Humaine.' What Gissing understood best was a particular section of the lower middle class; and if he had had health and encouragement, he was quite capable of weaving a lesser Human Comedy out of these materials. He seems to have emancipated himself very early from melodramatic leanings; and that fact alone would distinguish him the creator of the Rougon-Macquarts. But in no respects were the two alike. Zola was

from

a man of genius who 'mugged up' Bluebooks and such literature, and eked out with rhetoric and melodrama; but being a man of genius and a poet withal, he produced imperishable matter. Gissing was a writer of the highest talent, who described sincerely and most forcibly the world he knew." At the time of his death, George Gissing was employed on his new novel, which he had called "Veranilda"; but it is not known whether he had completed it.