"No one would ever have thought of teaching, or probably could have taught, the tumbler-pigeon to tumble,-an action which, as I have witnessed, is performed by young birds, that have never seen a pigeon tumble. We may believe that some one pigeon showed a slight tendency to this strange habit, and that the long-continued selection of the best individuals in successive generations made tumblers what they now are; and uear Glasgow there are housetumblers, as I hear from Mr. Brent, which cannot fly eighteen inches high without going head over heels. It may be doubted whether any one would have thought of training a dog to point, had not some one dog naturally shown a tendency in this line; and this is known occasionally to happen, as I once saw in a pure terrier: the act of pointing is probably, as many have thought, only the exaggerated pause of an animal preparing to spring on its prey. When the first tendency to point was once displayed, methodical selection and the inherited effects of compulsory training in each successive generation would soon complete the work; and unconscious selection is still at work, as each man tries to procure, without intending to improve the breed, dogs which will stand and hunt best."-pp. 214-15.

But what is there in nature that can supply the place of the judgment and will in the fancier, who pairs birds or dogs with the express intention of perpetuating a modification of the original form? According to our author one thing and one thing alone can do it. The multiplication of creatures on the face of the earth is out of proportion to their means of subsistence; this produces what he styles in his title "The Struggle for Life;" and those will survive and multiply that have some advantage over their competitors in the struggle. Every little variation, therefore, if it be advantageous to the individual, and in that case only, will be perpetuated. This involves, it need not be said, the extraordinary powers of inheritance, the singular property that all creatures possess of transmitting their own properties to their progeny. And the moment that we advert to this we are conscious of the very limited nature of our knowledge of the laws that govern inheri tance; for if the offspring inherits the parent's qualities, it inherits what the parent received: it has thus the tendency to have and to impart the image of the aboriginal parent, as well as the variations by which the successive generations have diverged from that standard, and, more mysterious still, the tendency to vary more or less has been transmitted also. What causes one of these tendencies to prevail at one time or under one condition rather

than another, so that now the progeny, retaining certain variations in other characters reverts to the ancestral type, now exactly represents its immediate parent, now again shows rather the inherited tendency to vary, we are profoundly ignorant.

That what Mr. Darwin has well called the Struggle for Life must be very severe, no one who remembers the extraordinary fertility of all nature, can possibly doubt.

"Linnæus has calculated that if an annual plant produced only two seeds-and there is no plant so unproductive as this-and their seedlings next year produced two, and so on, then in twenty years there would be a million plants. The elephant is reckoned the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase it will be under the mark to assume that it breeds when thirty years old, and goes on breeding till ninety years old, bringing forth three pair of young in this interval; if this be so, at the end of the fifth century there would be alive fifteen million elephants, descended from the first pair."-p. 61.

And this struggle will be felt most severely by those who are nearest of kin, for they feed on the same food, and are liable to the same casualties; and thus the tendency throughout nature will always be for those who have an advantage slowly to supplant their congeners, who have to work their way through the same difficulties, but under some less favourable condition. Thus, an increase of one variety will be at the expense of another variety of the same species, and the prevalence of one species will have been effected by the diminution of other species of the same genus, when, as is almost always the case, the field is already fully occupied. And the more numerous a species becomes, the better chance it will have in competition with its congeners; for the greater probability there will be of the appearance of advantageous variations, and the greater strength will be derived from the interbreeding, not too close, but with individuals in slightly varying conditions of life. This gives a decided advantage to the variety over the species, and to the specific form over the generic, giving thus, it is plain, a tendency to variation to all organic beings that are subject to severe competition. With nature, then, it is as with society. As the population increases, there is a greater number of claimants for every employment, and those who

are the best fitted for them, or have some other advantage over their rivals, obtain them, while sharp wits are at work devising some change or variety which may tell in their favour.

But it is not only with neighbours and kindred that the struggle prevails, but all nature acts and reacts upon its different parts. If an insect multiplies, it will be at the cost of some animal or plant, and to the benefit of some bird, and its prey or its enemies increasing or decreasing, will in their turn affect those with which they come in contact. A circle of this description is well worthy of quotation.

"From experiments which I have lately tried, I have found that the visits of bees are necessary for the fertilisation of some kinds of clover; but humble-bees alone visit the red clover (Trifolium pratense), as other bees cannot reach the nectar. Hence I have very little doubt, that if the whole genus of humble-bees became extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of

humble-bees in any district depends in a great degree on the number of field mice, which destroy their combs and nests; and Mr. H. Newman, who has long attended to the habits of humble-bees, believes that more than two-thirds of them are thus destroyed all over England.' Now the number of mice is largely dependent, as every one knows, on the number of cats; and Mr. Newman says, 'Near villages and small towns I have found the nests of humblebees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice.' Hence it is quite credible that the presence of the feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!"-pp. 73-74.

By the way, Mr. Darwin takes the opportunity of handling this portion of his subject to insert a most gratuitous sneer at the Flood, or rather at those who believe that the Scripture account of the Flood is true; for they, not knowing the causes of extinction, "invoke cataclysms to desolate the world." We suppose his idea is that, because the mutual dependence of organic beings is very perfect, and that a comparatively trifling accident could cause the undue predominance of one part, and consequent extinction of another, which extinction again will react and cause other extinctions, therefore the Deluge never occurred. It would be as true to say that because the organization of man is very delicate, that but a little will

disorder him, and but a little more will kill him, that therefore such wholesale destructions as the plague of Athens or of London never happened.

Mr. Darwin teaches that in producing variation, the direct effect of climate, food, and other external conditions of life, is not very great. But the indirect effect he considers to be exceedingly important. Sometimes it is difficult to know to which we are to attribute the change we see produced. For instance, animals of the same species have thicker and better fur in climates that are severely cold, and it is not easy to say how far the climate itself has improved the fur, or how far rather it has been that the warmest clad animals were best able to withstand the severe cold, and thus were the most likely to perpetuate their race, transmitting to their progeny their own peculiarity. But although the direct action of climate has probably not much further effect than that the sea air will render birds less bright coloured, shells brassy or lurid, and leaves in some degree fleshy, its indirect effect is powerful to an unknown degree. It influences parents to produce offspring, varying in some way from themselves, and of the laws of this influence we are quite ignorant. It can only be by an induction from a very large numberof facts that we can hope to come to any knowledge on this most interesting subject. It is, in fact, not only of great theoretical but also of practical importance, for it is the problem, the solution of which will enable us to domesticate many most useful creatures. What is it that affects the reproductive system? What are the causes throughout nature of fertility and sterility? These are secrets that nature will never entirely disclose, but we may learn much more than we already know; and as Mr. Darwin promises us in his forthcoming work "a large body of facts" which he has collected, bearing on the divergence from natural conditions which affects reproduction, we, together with, we should suppose, the Société d'Acclimatation and the Zoological Societies, and indeed with all friends of the farmyard and the cover, must look forward to its appearance with considerable interest.

Our author goes on to another cause of variation,-use and disuse. This, though by no means unimportant, seems to us to play a very inferior part in the plans of nature to that which we have just mentioned. Use, no doubt, is apt to strengthen and enlarge a member. With

most people the right hand is larger than the left, from this cause alone. The eye or the ear will, from constant use improve most astonishingly, and this we quite expect in persons who, like the blind or the deaf, have been obliged to rely more on one sense than others do. In the domestic duck, Mr. Darwin found that "the bones of the wing weigh less, and the bones of the leg more, in proportion to the whole skeleton than do the same bones in the wild duck." And disuse has also its physical effect upon the frame. "Not a single domestic animal can be named which has not in some country drooping ears; and the view suggested by some authors, that the drooping is due to the disuse of the muscles of the ears, from the animals not being much alarmed by danger, seems probable." (p. 11.) The description of the insects of Madeira, given from Mr. Wollaston, (p. 135) is most instructive. Out of the 550 species of beetles inhabiting the island, 200 are so far deficient in wings that they cannot fly; and of the twenty-nine endemic genera, no less than twenty-three genera have all their species in this condition. This Mr. Darwin thus explains: "During thousands of successive generations, each individual beetle which flew least, either from its wings having been ever so little less perfectly developed, or from indolent habit, will have had the best chance of surviving, from not being blown out to sea; and on the other hand, those beetles which most readily took to flight will oftenest have been blown to sea, and thus have been destroyed." Mr. Wollaston "suspects" that those insects which are not ground feeders, and which must habitually use their wings to gain their subsistence, have those members larger than usual. This our author accounts for on the score that the best fliers would most successfully battle with the winds. It is true that it is not easy to reconcile this with the " extraordinary fact of the almost entire absence of certain large groups of beetles, elsewhere excessively numerous, and which groups have habits of life almost necessitating frequent flight;" for one would have supposed that in such groups those with the strongest wings would have survived, and would have perpetuated a strong-winged race. Mr. Darwin should, we think, have told us more clearly whether, in this remarkable exemplification of a portion of his theory, any of the 200 species that in Madeira do not fly, have better wings, and fly more freely elsewhere, or whether it is only