century from the banks of the Volga. The black rat was almost as large and as strong as his adversary, but less ferocious and less prolific. It has been exterminated in spite of refuges which are inaccessible to its enemy. The mouse, which is much weaker, but at the same time much smaller, can retire into holes which are too small for the brown rat; it has therefore survived the black rat.

Is it possible to admit that selection and heredity act equally upon that indefinable something which is connected with the rudimentary intelligence and instincts of animals? With Darwin I unhesitatingly reply in the affirmative. With animals, as with man, all the individuals of the same species have not an equal amount of intelligence and do not invariably possess the same aptitudes; certain instincts, like certain forms, are capable of modification. Our domestic animals furnish a number of examples of these facts. The wild ancestors of our dogs were certainly not accustomed to point at game. When left to themselves and placed under new conditions of existence, animals sometimes change their manner of life entirely. Beavers, from being disturbed by hunters, have dispersed; they have now abandoned the construction of their lodges and dig out long burrows in the banks of rivers. The struggle for existence must have been favourable to the first discoverers of this new method of escaping from their persecutors, and natural selection, while preserving them and their descendants, has converted a sociable and constructive animal into a solitary and burrowing one.

Up to this point it is evident that I agree in all that Darwin has said on the struggle for existence and natural selection. I disagree with him when he attributes to them the power of modifying organised beings indefinitely in a given direction, so that the direct descendants of one species form another species distinct from the first.

IV. The fundamental cause of the disagreement arises evidently from the fact that Darwin had formed no clear conception of the sense which he attributed to the word

species. I have been unable to find in any of his works a single precise statement on this point. The accusation is more severe from being brought with justice against an author who claims to have discovered the origin of species.

More frequently Darwin seems to adhere to a purely morphological idea, which is also somewhat vague. He often opposes species and race, which he also calls variety, but without ever stating clearly what he understands by one or the other. He endeavours, moreover, to bring them together as closely as possible, though occasionally recognising some of the points which separate them. "The species," he says in drawing one of his conclusions, "must be treated as an artificial combination which is necessary for convenience." His disciples have followed him faithfully in this direction, and those who use the most explicit language on this subject, join their master in declaring that a species is only a kind of conventional group similar to those which are used in classification. As for races, they are only species undergoing transmutation. Now from what he has already learnt, short though the study has been, the reader knows, I hope, to which view he should adhere, and understands to what confusions such a vague kind of theory must lead.

In spite of the inevitable uselessness of a discussion of this kind, let us follow our adversaries into this unstable ground, and see whether morphological facts furnish their theory with the least probability.

Darwin himself, on several occasions, states that the result of selection is essentially to adapt animals and plants to the conditions of existence in which they have to live. Upon this point I agree with him entirely. If, however, harmony is once established between organised beings and the conditions of life, the struggle for existence and selection could only result in consolidating it and consequently their action is preservative.

If the conditions of life change they will again come into play in order to establish a new equilibrium, and modifications more or less marked will be the result of their action.

But will these modifications be sufficiently great to give rise to a new species? The following fact will serve as a reply.

At the present time there is a stag in Corsica, which from its form has been compared to the badger-hound: its antlers differ from those of European stags. Those who confine themselves to morphological characters, will assuredly ccnsider this as a distinct species, and it has often been considered to be so. Now Buffon preserved a fawn of this pretended species, and placed it in his park; in four years it became both larger and finer than the French stags which were older and considered finer grown. Moreover, the formal evidence of Herodotus, Aristotle, Polybius and Pliny attest that in their time there were no stags either in Corsica or Africa. Is it not evident that the stag in question had been transported from the continent to the island; that under the new conditions the species had undergone temporary morphological modification, though it had lost none of its power of resuming its primitive characters, when placed in its primitive conditions of life?

Are we, then, to conclude that in time nature could have completed the action, and entirely separated the Corsican stag from its original stock? We may answer in the negative, if any weight is to be attached to experience and observation.

Species partially subject to the rule of man furnish a number of facts which enable us to compare the power of natural forces, when abandoned to their own action, with that of man in modifying a specific type. In all artificial races varieties are infinitely more numerous, more varied and more marked than wild races and varieties. Now the result of these transmutations of organisms has only consisted in the formation of races, never in the formation of a new species. Darwin himself accepts this conclusion implicitly in his magnificent work on pigeons; for when speaking of the races of pigeons he only says that the difference of form is such that if they had been found in a wild state, we should have been compelled to make at least three or four genera of them. The wild rock pigeons, the original stock of all our

domestic pigeons, only differ, on the contrary, in shades of colour.

The result is always the same, whenever we can compare the work of nature with our own. When he has anything to do with any vegetable or animal species, man always changes its character, sometimes, after a lapse of some years, the change being much greater than that produced by nature since the species first came into existence. The effect of the conditions of life (milieu), of which we will speak presently, the struggle for existence and natural selection understood as I have just described it, the power which man possesses of directing natural forces and changing their resultant, easily explain this superiority of action.

Consequently, without leaving the domain of facts, and only judging from what we know, we can say that morphology itself justifies the conclusion that one species has never produced another by means of derivation. To admit the contrary is to call in the unknown, and to substitute a possibility for the results of experience.

Physiology justifies a still stronger assertion. Upon this ground also man is shown to be as powerful as nature, and for the same reasons. With our cultivated plants and domestic animals, it is not only the primitive form which has undergone change, but certain functions also. If we had only enlarged and deformed the wild carrot and the wild radish, it would not have become more eatable. To render it agreeable to our taste, the production of certain substances had to be reduced, and that of others enlarged, that is to say, nutrition and secretion had to be modified. If the functions in wild animal stocks had remained permanent, we should have had none of those races which are distinguished by a difference in the colour of the hair, in the production of milk, in aptitude for work, or in the production of meat. If. instinct itself had not obeyed the action of man, we should not have had in the same kennel, pointers, grey-hounds, truffle dogs and terriers.

Nature produces nothing like this. To admit that similar

results will one day follow from the action of natural forces is to appeal to the unknown, to possibility, and runs counter to all laws of analogy, and all the results furnished by experience and observation.

Man's superiority over nature is quite as clearly shown in the group of phenomena, which relate to the question with which we are now dealing.

We have seen how rare are the cases of natural hybrids among plants themselves; we have also seen that no cases are known among mammalia. Now since man has begun to make experiments in this direction, he has increased the number of hybrids among plants, and among animals also. Moreover, he has succeeded in preserving for more than twenty generations, a hybrid which he has been able to protect from reversion and disordered variation. But we know the care that was necessary to insure the continuance of agilops speltaformis. If this plant had been left to itself, it would soon have disappeared.

The single exception which is known confirms therefore the law of sterility among species left to themselves. Now this law is in direct opposition to all the theories, which like Darwinism, tend to confuse species and race. This has been clearly understood by Huxley and has caused him to say, “I adopt the theory of Darwin under the reserve that proof should be given that physiological species can be produced by selective crossing."

This proof has not yet been given, for it is a strange abuse of words to call by the name of species, the series of hybrids whose history I have given above, viz.: the leporides and the chabins. But even if the proof demanded by Huxley were furnished, it does not follow that the greatest objection to the Darwinian theories would be removed.

In fact, in this theory, as in all those which rest upon gradual transmutation the new species derives its origin from a variety, possessing a character which is at first rudimentary, but which is developed very gradually, making some progress in each generation. The result of this is that