to cite what Dr. Kidd calls an "undesigned experiment," which to my mind
goes far to prove that the effects of prolonged friction on the human
body during many generations is not heritable. The custom followed by
many Bantu tribes of producing in their women an elongation of the
genital parts by constant manipulation must have been practiced during
very many generations, certainly much longer than the comparatively
recent harnessing of horses in England, for we know how tenaciously
primitive people cling to their old customs, generation after
generation, for thousands of years, and yet no instance has ever been
noticed by these people, who are very observant in these matters, of any
sign of such an inherited characteristic in any of their female
children.

The ordinary layman, though he may feel strongly interested in the
problems of heredity and evolution, has seldom the leisure or the
opportunity for the careful study of biological data, and he must
therefore leave these to the specialists in scientific enquiry, but he
is by no means precluded from using his own common-sense in drawing
conclusions from the ordinary plain facts of life observable around him.
It is when we come to consider this most important question in its
bearing upon the mental side of the human being that the ordinary layman
feels himself to be no less competent to form an opinion than the
trained man of science.

Is it possible, then, we ask, for the parent whose intellect has been
developed through training in his lifetime to transmit to his children
any portion of this acquired increment of mental capacity, or, putting
the question in more concrete terms, is it possible for a parent to
transmit to his offspring any part of that power to increase the size
and quality of the brain which may be assumed to have resulted in his