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.