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 consider 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.