were not successful.  People do not become rich because the poor in large numbers go away, but because they have been lucky, or provident, or more commonly both.  If they would keep their wealth when they have made it they must exclude luck thenceforth to the utmost of their power and their children must follow their example, or they will soon lose their money.  The fact that the weaker go to the wall does not bring about the greater strength of the stronger; it is the consequence of this last and not the cause—­unless, indeed, it be contended that a knowledge that the weak go to the wall stimulates the strong to exertions which they would not otherwise so make, and that these exertions produce inheritable modifications.  Even in this case, however, it would be the exertions, or use and disuse, that would be the main agents in the modification.  But it is not often that Mr. Wallace thus backslides.  His present position is that acquired (as distinguished from congenital) modifications are not inherited at all.  He does not indeed put his faith prominently forward and pin himself to it as plainly as could be wished, but under the heading “The Non-Heredity of Acquired Characters,” he writes as follows on p. 440 of his recent work in reference to Professor Weismann’s Theory of Heredity:—­

“Certain observations on the embryology of the lower animals are held to afford direct proof of this theory of heredity, but they are too technical to be made clear to ordinary readers.  A logical result of the theory is the impossibility of the transmission of acquired characters, since the molecular structure of the germ-plasm is already determined within the embryo; and Weismann holds that there are no facts which really prove that acquired characters can be inherited, although their inheritance has, by most writers, been considered so probable as hardly to stand in need of direct proof.

“We have already seen in the earlier part of this chapter that many instances of change, imputed to the inheritance of acquired variations, are really cases of selection.”

And the rest of the remarks tend to convey the impression that Mr. Wallace adopts Professor Weismann’s view, but, curiously enough, though I have gone through Mr. Wallace’s book with a special view to this particular point, I have not been able to find him definitely committing himself either to the assertion that acquired modifications never are inherited, or that they sometimes are so.  It is abundantly laid down that Mr. Darwin laid too much stress on use and disuse, and a residuary impression is left that Mr. Wallace is endorsing Professor Weismann’s view, but I have found it impossible to collect anything that enables me to define his position confidently in this respect.