forthcoming.

After all, the plain man must remember that the effects of use and
disuse, which he seems to see everywhere about him, are mixed up with
plenty of apparent instances to the contrary. He will smile, perhaps,
when I tell him that Weismann cut off the tails of endless mice, and,
breeding them together, found that tails invariably decorated the race
as before. I remember hearing Mr. Bernard Shaw comment on this
experiment. He was defending the Lamarckianism of Samuel Butler, who
declared that our heredity was a kind of race-memory, a lapsed
intelligence. "Why," said Mr. Shaw, "did the mice continue to grow
tails? Because they never wanted to have them cut off." But men-folk
are wont to shave off their beards because they want to have them off;
and, amongst people more conservative in their habits than ourselves,
such a custom may persist through numberless generations. Yet who ever
observed the slightest signs of beardlessness being produced in this
way? On the other hand, there are beardless as well as bearded races
in the world; and, by crossing them, you could, doubtless, soon produce
ups and downs in the razor-trade. Only, as Weismann's school would
say, the required variation is in this case spontaneous, that is, comes
entirely of its own accord.

Leaving the question of use-inheritance open, I pass on to say a word
about variation as considered in itself and apart from this doubtful
influence. Weismann holds, that organisms resulting from the union
of two cells are more variable than those produced out of a single
one. On this view, variation depends largely on the laws of the
interaction of the dissimilar characters brought together in
cell-union. But what are these laws? The best that can be said is that
we are getting to know a little more about them every day. Amongst