Thus does the author of the “Vestiges” revel amidst the sublimities and copious materials of his subject. Time and space, the elements of the astral heavens and the earth, are alike indefinitely in his grasp. That he has failed to frame a better system of things than the one we see actually around us, is a necessary consequence of the restraints imposed on human investigation. Facts will not be supplanted by any heights, or depths, or ingenuities of speculation. And as existing nature is all against the doctrine of transmutation and development, so the discoveries of geology through all its formations are equally opposed to such views of creation. A short sketch of both will abundantly illustrate this. As to the course of living nature, the development theory is there at once repudiated in the now clearly established fact, that the first germinal vesicles are different in the different tribes of animals. A non-identity of type is discoverable in the minutest microscopical beginnings of organic life. And “by no change of conditions can two ova of animals of the same species be developed into different animal species; neither by any provision of identical conditions can two ova of different species be developed into animals of the same kind.” Corresponding to these differences in their fœtal forms, there are in all the stages toward parturition a similarity of progress in the various organs and appendages in the same kinds of animals. Fishes, birds, quadrupeds, all manifest a divergence from each other in the first action of the respirating organs—in the nervous system—and in all the apparatus connected with the movements of the heart and blood-vessels. There is no structural interchange, in the minutest part, that distinguishes the orders of the perfect animal in any of the antecedent fœtal conditions; the organic contrivances within the egg being as complete and as thoroughly prospective to the future use and habits of the bird, as are the petals of the flower inclosed within the bud, the arms of the giant oak within the acorn, or man in his evolving capacity toward intellectual being.