Weismann’s statement that the power of regeneration has decreased “in correspondence with the increase in the complexity of the part” cannot by any means be entirely accepted. If the complexity of a part is of such a kind that the part cannot sustain itself independently until regeneration has taken place, or if the exposed surface of the wound is such that it cannot be closed over, or if the new part cannot be properly nourished, or if the tissues have changed in such a way that their cells can no longer multiply, then the statement is, to a certain extent, true. On the other hand, when we find that one of the most complicated organs of the body, the eye, can regenerate in the salamander, if only a piece of the optic cup is left attached to the nerve, we may well doubt if there is any such direct and general connection between regeneration and complexity as Weismann maintains. Weismann’s so-called “mechanism” of qualitative nuclear division is the basis of his conception of pre-formation. We are, I think, at present in a position to reject not only this conception, since it finds no support either in observation or experiment, but also his view that regeneration is brought about by latent cells; for it has been shown in a large number of cases that the new cells come directly from the old, differentiated ones. In a previous chapter it has been pointed out that Weismann’s idea that regeneration has been acquired by a process of natural selection, and is under the influence of this supposed agent, is in direct contradiction to a number of known facts. Under these circumstances we are warranted, I think, in concluding that the entire Weismannian point of view is wrong.