pitulation requires if its occurrence be general), then condensation cannot be caused by natural selection because accelerated adult features often have no function in juvenile descendants. It must then be the result of some principle of inheritance. Not only does this principle work independently of natural selection (thereby compromising the general importance of Darwin's postulate), but it is also completely unknown:
Newly acquired characters undergo, as a whole, backward transference, by which means they are to a certain extent displaced from the final ontogenetic stage by characters which appear later. This must be a purely mechanical process, depending on that innate law of growth, the action of which we may observe without being able to explain fully. (1881, p. 280)
Yet, through a glass darkly, Weismann glimpsed the direction of the coming solution. The laws of heredity must first be established: "If we could see the determinants, and recognize directly their arrangement in the germ-plasm and their importance in ontogeny, we should doubtless understand many of the phenomena of ontogeny and their relation to phylogeny which must otherwise remain a riddle" (1904, p. 189).
The determinants were soon elucidated as Mendelian genes; but Weismann's idea of universal recapitulation did not survive. He knew that no proper test could be made in the absence of a theory of inheritance; he could not know that the coming theory would invalidate his own conviction. We will return to the fate of recapitulation in Chapter 6, following a discussion in Chapter 5 of the remarkable influence that recapitulation exerted in fields as diverse as politics and primary education.
Appendix: The Evolutionary Translation