But although this seems to me sufficiently obvious, as I have shown at greater length in the _Examination of Weismannism_, it must not be understood that I hold that there is room for any large amount of such overlapping. On the contrary, it appears to me as certain as anything can well be that the amount of such overlapping from one generation to another, if it ever occur at all, must be exceedingly small, so that, if we have regard to only a few sequent generations, the effects of use-inheritance, and Lamarckian factors are, at all events as a rule, demonstrably imperceptible. But this fact does not constitute any evidence--as Weismann and his followers seem to suppose--against a possibly important influence being exercised by the Lamarckian factors, in the way of gradual increments through a long series of generations. It has long been well known that acquired characters are at best far less fully and far less certainly inherited than are congenital ones. And this fact is of itself sufficient to prove the doctrine of continuity to the extent that even the Lamarckian is rationally bound to concede. But the fact yields no proof--scarcely indeed so much as a presumption--in favour of the doctrine of continuity as absolute. For it is sufficiently obvious that the adaptive work of heredity could not be carried on at all if there had to be a discontinuity in the substance of heredity at every generation, or even after any very large number of generations. Little more need be said concerning the arguments which fall under the headings A and B. The Indirect evidence is considered in Appendix I of the _Examination of Weismannism_; while the Direct evidence is considered in the text of that work in treating of Professor Weismann's researches on the _Hydromedusae_ (pp. 71-76). The facts of karyokinesis are generally claimed by the school of Weismann as making exclusively in favour of continuity as absolute. But this is a partisan view to take. In any impartial survey it should be seen that while the facts are fairly interpretable on Weismann's theory, they are by no means proof thereof. For any other theory of Heredity must suppose the material of heredity to be of a kind more or less specialized, and the mechanism of heredity extremely precise and well ordered. And this is all that the facts of karyokinesis prove. Granting that they prove continuity, they cannot be held to prove that continuity to be absolute. In other words, the facts are by no means incompatible with even a large amount of commerce between germ-plasm and somato-plasm, or a frequent transmission of acquired characters.