I am bound to add, that some of the facts and arguments here used by me, have been advanced for the same purpose in an able article lately published in the "Medico-Chirurgical Review.

" At the present day almost all naturalists admit evolution under some form.

Mr.

Mivart believes that species change through "an internal force or tendency," about which it is not pretended that anything is known.

That species have a capacity for change will be admitted by all evolutionists; but there is no need, as it seems to me, to invoke any internal force beyond the tendency to ordinary variability, which through the aid of selection, by man has given rise to many well-adapted domestic races, and which, through the aid of natural selection, would equally well give rise by graduated steps to natural races or species.