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 _Ægilops speltæformis_. 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 between successive individuals the only difference is that of _race_. Now, as we have seen, the fertility among races of the same species remains constant, and consequently, in the hypothesis of Darwin, as in that of Lamarck, etc., the fertile crossings would in every sense of the word constantly confuse the original and the derived species which was in process of formation. The same cause having produced the same effects since the commencement of the world, the organic world would present the greatest confusion instead of its well-known order.