Let us now further examine the supposed kinship of man with the monkey, as evidenced by the similarity of the structure of the brains of the two animals, in reference to the supposed process of evolution as the means of accounting for the origin of two species so essentially distinct. How has it happened that different species have become completed and final types, transmitting, after they have become completed, one and the same type, by the ordinary process of generation, and not admitting of the sexual union with any other distinct species? On the theory of the evolution of animal out of animal, we must suppose that at some time the secondary causes of natural and sexual selection have done their work. It ends in the production of a species which thereafter remains one and the same animal, and Nature has established a barrier to any sexual union with any other species. If we give the rein to our imaginations, and, taking the process of evolution as it is described to us, suppose that in the long course of countless ages the struggle for existence among very numerous individuals has led to gradual transformations of structure which the sexual selection has transmitted to offspring, and so a new animal has at length been formed through the successive "survivals of the fittest," we reach an animal of a new species, and that species, under no circumstances, produces any type but its own, so far as we have any means of knowledge. All the knowledge respecting the ape that has been accumulated shows only that this species of animal, since it became a completed type, has procreated its own type and no other. Whatever struggle for existence the individuals of this type have had to undergo, whatever modifications of structure or habits of life the survival of the fittest individuals of this type may have produced from the earliest imaginable period until the present time, the fact remains that this species of animal is a completed and final product. At the same time we have another completed and final type of animal known as man, which, so long as he has been known at all, is a distinct and peculiar species. Between the brain of this animal and the brain of the other we find certain strong resemblances. In each of them this organ is a structure performing the same office in the animal mechanism, with adaptations peculiar to the varying structure of each of them. In order to justify the conclusion that the one animal is a modified descendant from the other, so as to exclude the hypothesis that the resemblances of any one or of all of their respective organs was a result of the adoption of a general plan in special creations of distinct species, we ought to find some instance or instances in which the completed animal called the ape has been developed into an animal approaching more nearly to man than the man, as he is first known to us, approached to the first ape that is known to us. Without such