1. That the two causes, natural and sexual selection, have probably exercised some influence in the modification of animal forms; but that the laws of probability preclude our entertaining the belief that these causes can have had, by themselves, and apart from a superintending power, anything beyond a very limited operation. 2. That in cases where there have been related changes in different parts of the same organism, or in different organisms, the inadequacy of these two causes is virtually admitted by the introduction of certain supposed laws; and that these laws, being defined by Mr. Darwin to be no more than "the ascertained sequence of events," cannot be regarded as efficient causes, and so cannot supply the defect. 3. That there are particular points in the chain of life, in which the transition from one form to another is so great, and so incapable of graduation, that it is impossible to suppose that these two causes can have been adequate to produce it. Of this a notable instance is to be found in the transition from oviparous animals to the mammalia. We come now to the consideration of the origin of man, which Mr. Darwin, in his last work, ascribes also to natural and sexual selection. His view is, that man is descended from some family of anthropomorphous apes, and that all those enormous differences which, as he admits, exist between the highest ape and the most degraded member of the human race, are differences of degree only, and not of kind; that all our intellectual wealth, and all our moral laws, are simply the development of faculties and ideas which were possessed in a ruder form by the creatures from whom man is descended. So far as man's physical constitution is concerned, there is undoubtedly something to be said in favour of this view. For man's bodily frame is composed of the same elements, and moulded upon the same general plan as that of the higher apes, and, what is still more remarkable, it retains, in a rudimentary form, certain muscles and organs which are fully developed and answer important purposes in many of the quadrumana. Of these the tail is a remarkable instance. But when the differences between the physical peculiarities of man, and those of his supposed progenitors are examined, the theory of natural selection collapses entirely, for the development has taken the form which would be most disadvantageous in the struggle of life. This is very clearly put by the Duke of Argyll.[Footnote: "Recent Speculations on Primeval Man," in Good Words, April, 1868.]