140 Darwin, and after Darwin. 



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 La- 

 marckian 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 im- 

 portant 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 con- 

 genital 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 suffi- 

 ciently 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 argu- 

 ments 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 

 Hydro-medusae (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 



