ignorance, and so high our presumption, that we marvel when we hear of the extinction of an organic being; and as wo do not seo the cause, wo invoke cataclysms to desolato the world, or invent laws on the duration of the forms of life!"—(pp. 72, 78.)

"When wo look at the plants and bushes clothing an ontangled bank, wo aro tempted to attributo their proportional numbers and kinds to what wo call chanco. But how falno a view is this! Every ono has heard that when an American forest is cut down, a very different vegetation springs up; but it has been observed that the trees now growing on the ancient Indian mounds, in the Southern United States, display the same beautiful diversity and proportion of kinds as in the surrounding virgin forests, What a strugglo between the several kinds of trees must here have gone on during long centuries, each annually scattering its seeds by the thousand; what war botween insect and insect-between insects, snails, and other animals, with birds and beasts of prey-all striving to increnso, and all feeding on each other or on the trees, or their seeds and seedlings, or on the other plants which first clothed the ground And thus checked the growth of the trees! Throw up a handful of feathers, and all must fall to the ground according to definito laws; but how simple is this problem compared to the action and reaction of tho innumerablo plants and animals which have determined, in the course of centuries, the proportional numbers and kinds of trees now growing on the old Indian ruins!"-(pp. 74, 75.)

For reasons obvious upon reflection, the competi tion is often, if not generally, most severo betwen nearly related species when they are in contact, 80 that one drives the other before it, as the Hanoverian the old English rat, the small Asiatic cockroach in Russia, its greater congener, etc. And this, when duly considered, explains many curious results; such, for instance, as the considerable number of different genera of plants and animals which are generally found to inhabit any limited area.

"The truth of the principle that the greatest amount of life can be supported by great diversification of structure is seen under many natural circumstances. In an extremely small area, especially if freely open to immigration, and where the contest between individual and individual must bo sovoro, wo always find great diversity in its inhabitants. For instance, I found that a ploco of turf, three feet by four in size, which had been exposed for many years to exactly the same conditions, supported twenty species of plants, and theso belonged to eighteen gonern, and to eight orders, which showed how much thesO plants differed from each other. So it is with the plants and insects on small and uniform islets; and so in small ponds of fresh water. Farmers find that they can raise most food by a rotation of plants belonging to the most different orders; Naturo follows what may be called a simultaneous rotation. Most of the animals and plants which live close round any small piece of ground could live on it (supposing it not to be in any way peculiar in its nature), and may be said to be striving to the utmost to live there; but it is soon that, where they come into the closest competition with each other, tho advantages of diversi fleation of structure, with the accompanying differences of habit and constitution, determino that the inhabitants, which thus Jostlo each other most closely, shall, as a general rule, belong to what wo call different genera and orders."-(p. 114.)

The abundance of some forms, the rarity and final extinction of many others, and the consequent diver getico of character or increase of difference among the surviving representatives, are other consequences. As favored forms increase, the less favored must dimin ish in number, for there is not room for all; and the lightest advantage, at first probably inappreciable to human observation, must decide which shall prevail and which must perish, or be driven to another and for it more favorable locality.

Wo cannot do justico to the interesting chapter

upon natural selection by separated extracts. Tho following must serve to show how the principle is sup posed to work:

"If during the long course of ages, and under varying condi tions of life, organic beings vary at all in the several parts of their organization, and 1 think this cannot bo disputed; if there be, owing to the high geometrical powers of increase of each species, at some ago, season, or year, a severo struggle for life, and this certainly cannot be disputed: then, considering tho infinito complexity of the relations of all organic beings to each other and to their conditions. of existence, causing an infinito diversity in structure, constitution, and habits, to be advantageous to them, I think it would be a most extraordinary fact if no variation ever had occurred useful to each being's own welfare, in the same way as so many variations have occurred useful to But if variations useful to any organic being do occur, assuredly individuals thus characterized will have tho best chance of being preserved in the struggle for life; and from the strong principle of inheritance they will tend to produce offspring similarly characterized. This principle of preservation I have called, for the sake of brevity, Natural Selection."-(pp. 126, 127.)

man.

"In order to make it clear how, as I believe, natural selection acts, I ́must beg permission to give one or two imaginary illustrations. Let us take the caso of a wolf, which preys on various animals, securing sono by craft, some by strength, and some by fleetness; and let us suppose that the fleetest prey, a deer for instance, had from any chango in the country increased in numbers, or that other prey had decreased in numbers, during that season of the year whon the wolf is hardest pressed for food. I can under such circumstances seo no reason to doubt that the swiftest and slimmest wolves would have the best chance of surviving, and so be preserved or selected-provided always that they retained strength to master their prey at this or at some other period of the year, when they might bo compelled to prey on other animals. I can seo no moro reason to doubt this than that man can improve the fleetness of his

greyhounds by careful and methodical selection, or by that unconscious selection which results from each man trying to keep the best dogs without any thought of modifying the breed.

"Even without any change in the proportional numbers of the animals on which our wolf preyed, a cub might be born with an innate tendency to pursue cortain kinds of proy. Nor can this be thought very improbable; for we often observe great differences in the natural tendencies of our domestic animals: one cat, for instance, taking to catching rats, another mico; ono cat, according to Mr. St. Jolin, bringing home winged game, another hares or rabbits, and another hunting on marshy ground, and almost nightly catching woodcocks or snipes. The tendency to catch rats rather than mice is known to be inherited. Now, if any slight innate change of habit or of structure benefited an individual wolf, it would have the best chance of surviving and of leaving offspring. Some of its young would probably inherit the same habits or structure, and by the repotition of this process a new variety might be formed which would either supplant or coexist with the parent-form of wolf. Or, again, the wolves inhabiting a mountainous district, and those frequenting the lowlands, would naturally be forced to hunt different prey; and from a continued preservation of the individuals best fitted for the two sites, two varieties might slowly bo formed. Theso varieties would cross and blend where they met; but to this subject of intercrossing we shall soon have to return. I may add that, according to Mr. Pierce, there are two varieties of the wolf inhabiting the Catskill Mountains in the United States, one with a light greyhound-like form, which pursues deer, and the other more bulky, with shorter legs, which more frequently attacks tho shepherd's flock."-(pp. 90, 91.)

Wo eko out the illustration here with a counterpart instance, viz., the remark of Dr. Bachman that "the deer that reside permanently in the swamps of Carolina are taller and longer-legged than those in the higher grounds." "

"Quadrupeds of America," vol. ii., p. 289.

The limits allotted to this article are nearly reached, yet only four of the fourteen chapters of the volumo have been touched. These, however, contain tho fundamental principles of the theory, and most of those applications of it which are capable of something like verification, relating as they do to the phenomena now occurring. Some of our extracts also show how these principles are thought to have operated through the long lapse of the ages. The chapters from the sixth to the ninth inclusive are designed to obviate difficulties and objections, "some of them so grave that to this day," the author frankly says, he "can never reflect on them without being staggered." We do not wonder at it. After drawing what comfort he can from "the imperfection of the geological record" (Chapter IX.), which we suspect is scarcely exag gerated, the author considers the geological succession of organic beings (Chapter X.), to see whether they better accord with the common view of the immutability of species, or with that of their slow and gradual modification. Geologists must settle that question. Then follow two most interesting and able chapters on the geographical distribution of plants and animals, the summary of which we should be glad to cite; then a fitting chapter upon classification, morphology, embryology, etc., as viewed in the light of this theory, closes the argument; the fourteenth chapter being a recapitulation.

The interest for the general reader heightens as the author advances on his perilous way and grapples manfully with the most formidable difliculties.

To account, upon these principles, for the gradual