earch may reveal an intimate connection between peculiarities of
pigmentation and peculiarities of mind.

The inheritance of mental characters is often elusive, for it is frequently
difficult to appraise the effects of early environment in determining a
man's bent. That ability can be transmitted there is no doubt, for this is
borne out by general experience, as well as by the numerous cases of able
families brought together by Galton and others. But when we come to inquire
more precisely what it is that is transmitted we are baffled. A
distinguished son follows in the footsteps of a distinguished father. Is
this due to the inheritance of a particular mental aptitude, or is it an
instance of general mental ability displayed in a field rendered attractive
by early association? We have {180} at present very little definite
evidence for supposing that what appear to be special forms of ability may
be due to specific factors. Hurst, indeed, has brought forward some facts
which suggest that musical sense sometimes behaves as a recessive
character, and it is likely that the study of some clean-cut faculty such
as the mathematical one would yield interesting results.

The analysis of mental characters will no doubt be very difficult, and
possibly the best line of attack is to search for cases where they are
associated with some physical feature such as pigmentation. If an
association of this kind be found, and the pigmentation factors be
determined, it is evident that we should thereby obtain an insight into the
nature of the units upon which mental conditions depend. Nor must it be
forgotten that mental qualities, such as quickness, generosity,
instability, etc.,--qualities which we are accustomed to regard as
convenient units in classifying the different minds with which we are daily
brought into contact,--are not necessarily qualities that correspond to
heritable units. Effective mental ability is largely a matter of
temperament, and this in turn is quite possibly dependent upon the various
secretions produced by the different tissues of the body. Similar nervous
systems associated with different livers might conceivably result in
individuals upon whose mental ability the world would pass a very different
judgment. Indeed, it is not at all impossible {181} that a particular form
of mental ability may depend for its manifestation, not so much upon an
essential difference in the structure of the nervous system, as upon the
pr