The theory of descent is indeed at first sight exceedingly plausible, and will probably always be the _directive_ for all future investigations as to the origin of species. The organic species show, besides the great variety of their characteristics and the unchangeable nature of these characteristics, many other qualities which are common to them; and these common characteristics are precisely those which are most essential. {62} Moreover the higher the structure of the organisms which are differentiated, the more numerous and more valuable will become the evidences of similarity, and the greater also will be their distance from the inorganic and from the lowest organisms of their class, their type, or their kingdom. For instance, rose and apple-tree, elder and ash, wolf and dog, goat and sheep, ape and man, are not only a great deal farther removed from the mode of existence of inorganic bodies than the algae, the monera, and other low organisms, but they have also, in spite of the great interval which separates them from one another and especially which separates man from every animal, much more numerous and important points of contact than, for instance, two families or genera of algae or of mosses, of polyps or of infusoria, have among one another. Now our imagination refuses to accept the theory that the Creator, or nature, or whatever we wish to call the principle generating the species, in producing the new species, laid aside all those points of contact which are continually becoming more numerous and more important, and produced instead, by ever widening leaps, the new and higher species from the inorganic, which lies farther and farther from them. On the other hand, the theory appears to us all the more plausible, that every new species came into existence on that stage which is the most nearly related to it, and which was already in existence. If we add further, that the two old maxims of the natural scientists, _omne vivum ex ovo_ and _omne ovum ex ovario_, have not been invalidated, in spite of all the searching for a _generatio aequivoca_, and that, even if the origination of the lowest organisms out of the inorganic could in future be {63} proved, yet the truth of these maxims for all the higher organized individuals is established as a fact without exception. Moreover, if we take into consideration the fact that we can not at all imagine either the origin or the first development of a higher animal or a human organism without the protecting integument and the nourishing help of a mother's womb, we may venture to say that each and every attempt to render the origin of the first individuals of the higher species conceivable, leads of necessity to the descent theory. We have either to reject, once for all, such an attempt, as an unscientific playing with impossibilities, or to accept the idea of descent. It is certainly the lasting merit of Darwin, even if his whole structure of proofs should in the course of time show