38 DANIEL WILSON ON THE RIGHT 
weight, of the left over the right cerebral hemisphere, also ascribes the source of this to 
the greater frequency and energy of all right-hand movements. Hereverts to an argument 
derived from left-handedness when discussing his theory that the two hemispheres practi- 
cally constitute two distinct brains, each sufficient in itself for the full performance of 
nearly all mental operations, though each has also its own special functions, among 
which is the control over the movements and the organs of opposite sides of the body. 
“ Every organ,” he says, “ which is put in use for a certain function gets developed, and 
more apt or ready to perform that function. Indeed, the brain shows this in point of mere 
size ; for the left side of the brain, which is used most, is larger than the right side. The 
left side of the brain also receives a great deal more blood than the right side, because 
its action preponderates; and every organ that acts much receives more blood.” He 
accordingly affirms that the growth of the brain up to forty years of age, if not indeed to a 
considerably later period of life, is sufficiently marked to require the continued enlargement 
of the hat. Speaking of himself, as having then passed his fifty-sixth year, he says:— 
“There is no period of six months that has passed that I have not found my hat, if 
neglected and put aside, has become too small. The head growing is very strong proof 
that the brain grows also.” The opinions advocated by the leading anatomists of Hurope 
in the earlier years of the present century, differed widely from this. It was indeed 
maintained by Semmering, the Wenzels, and Tiedemann, that the brain attained its 
greatest development not later than at seven or eight years of age. But, without going 
so far as Dr. Brown-Sequard is prepared to do, the old idea as to the complete develop- 
ment of the brain in youth is now abandoned, and the latest observers have produced 
evidence in proof of the brain increasing in weight, so that the greatest average weight 
occurs between thirty and forty years of age. They do not, however, indicate any such 
increase in actual bulk as Dr. Brown-Sequard implies. In the majority of cases, 
indeed, the comparatively early ossification of the sutures would alone suffice to 
preclude the possibility of such a growth of the head, as Dr. Brown-Sequard 
assumes to be demonstrable even beyond the age of fifty-six. Without due 
allowance for the stiffness of a new hat, and the shrinking of an old one when out of use, 
hat-measurements may prove very deceptive. On his assumption relative to the normal 
excess of the left hemisphere of the brain, there ought to be a greater equality between 
the two hemispheres in a left-handed than a right-handed person, owing to the more 
equal employment of the two sides of the brain by the latter. But he fails to appreciate 
the bearings of his own argument in the case of a left-handed person conforming in many 
ways to the usage of the majority, yet instinctively giving the preference to the left hand. 
He dwells on the fact that very few left-handed persons have learned to write with the 
left hand, and that those who can do not write nearly so well with it as with the right 
hand. Even in persons who are left-handed naturally, so that the right side of the brain 
may be assumed to control the reasoning faculties and their expression, he argues that the 
left side of the brain “can be so educated that the right hand, which that side of the 
brain controls, produces a better handwriting than that by the left hand, though that is 
controlled by the better developed brain.” But the reasoning is alike partial and mislead- 
ing. The left-handed person systematically submits to disabilities in his efforts to comply 
with the usage of the majority, not only in holding his pen in the right hand, but in the 
direction and slope of the writing. A left-handed race would naturally write from right 
