i 
_ or diminution of the body. 
NERVOUS CENTRES. (Human Anatomy. Tue Encepuaton.) 
(2lbs. 90z. 1dr. I have generally found the 
cavity of the skull smaller in old men than in 
_ middle-aged persons. It appears to me, there- 
fore, probable that the brain really decreases in 
old age, only more remarkably in some persons 
i than in others. 
“5. There is undoubtedly a very close con- 
nection between the absolute size of the brain 
and the intellectual powers and functions of the 
mind. This is evident from the remarkable 
smallness of the brain in cases of congenital 
idiotismus, few much exceeding in weight the 
brain of a new-born child. Gall, Spurzheim, 
Haslam, Esquirol, and others have already ob- 
served this, which is also confirmed by my own 
researches. The brain of very talented men, 
on the other hand, is remarkable for its size. 
« Anatomists differ very much as to the weight 
__ of the brain compared with the bulk and weight 
_ of the body; for the weight of the body varies 
_ so much, that it is impossible to determine 
_ accurately the proportion between it and the 
brain. 
~ to 800 lbs., and changes both in health and 
: when under the influence of disease, depending 
The weight of an adult varies from 100 
‘m great measure on nutrition. The weight of 
_ the brain, although different in adults, remains 
generally the same, unaltered by the increase 
; Thin persons 
have, therefore, relative to the size of the 
_ body, a larger brain than stout people. 
“From my researches I have drawn the fol- 
lowing conclusions. 
_ 1, The brain of a new-born child is, rela- 
_ tively to the size of the body, the largest ; the 
proportion is 1: 6. 
_* 2. The human brain is smaller, in compa- 
__ tison to the body, the nearer inan approaches to 
his full growth. In the second year the pro- 
" portion of the brain to the body is as 1:14; in 
the third, 1: 18; in the fifteenth, 1:24. In 
_a full-grown man, between the age of twenty 
and seventy years, as1:35to45. In lean 
“persons the proportion is often as 1: 22 to 27; 
in stout persons, as 1 : 50 to 100 and more.” 
_ (This estimate, as far as regards the early 
ages, differs from that of Dr. John Reid, pro- 
bably owing to the difference in the number 
weighed.) 
__ * 3. Although Aristotle hasremarked that the 
female brain is absolutely smaller than the male, 
‘it is nevertheless not relatively smaller com- 
pee with the body; for the female body is, 
in general, lighter than that of the male. 
The female brain is for the most part even 
Targer than the male, compared with the size 
of the body. 
_ “The different degree of susceptibility and 
Sensibility of the nervous system seems to de- 
pend on the relative size of the brain as com- 
} pared with the body. (qu.?) Children and 
young people are more susceptible, irritable, 
and sensitive than adults, and have a relatively 
larger brain. Thin persons are more suscep- 
ible than stout. In diseases which affect the 
nourishment of the body, the susceptibility 
icreases as the patients grow thinner. The 
Susceptibility and sensibility decreases, on the 
| other hand, with persons recovering from a 
665 
long illness, gradually as they regain their 
strength. The degree of eo SN 
is also in proportion to the size of the brain. 
Mammalia and birds have a larger brain and 
are more susceptible than amphibious animals 
and fishes.”’* 
Enough has been said to show, that in con- © 
trasting the brain of man and that of the lower 
animals, with reference to the much agitated 
question of the connexion of mental faculties 
and intellectual endowments with that organ, 
no one standard of comparison must be se- 
lected. We must look to absolute and relative 
size—we must compare the bulk of the several 
portions of the encephalon with each other— - 
we must notice the size of the encephalic 
nerves in relation to the whole organ—and, 
above all, we must compare the intimate or- 
ganization of brain one with the other. Unless 
all the features of the brains that are subjected 
to comparison be carefully taken into the ac- 
count, erroneous conclusions will be obtained. 
For instance, the brain of the elephant is ab- 
solutely larger than that of mau: the convo- 
lutions of the hemispheres are very highly de- 
veloped, and exhibit a degree of complexity 
almost equal to that of the human brain. At 
first sight we might be led to infer a very close 
approximation to the human, and place the 
elephant very high up in the scale of cerebral 
developement. In comparing, however, the 
brain of this animal with that of the monkey, 
the following result is obtained. The encepha- 
lon of the elephant is above that of the monkey 
by the superior developement of the cerebral 
convolutions; it is equal to it, as regards the 
quadrageminal bodies, but from the general 
form of the brain, the length of its transverse 
diameter, the presence of olfactory eminences, 
the position of the cerebellum (uncovered by 
the posterior lobes), it must be placed on a level 
with that of the inferior Mammalia.t 
Of the brain in different races of mankind. 
—When so much diversity is observable in the 
form of the cranium in different races of man- 
kind, it seems reasonable to expect a corres- 
ponding variety in the shape and other charac- 
ters of the encephalon. The external form of 
this latter organ will correspond with that of the 
cranium, and its size with the capacity of that 
cavity. But it is plain that as the capacity of 
the skull is no wise necessarily affected by its 
shape, so the absolute bulk of the brain need 
not vary, although its containing case may ex- 
hibit much variety of form. The great ques- 
tion for the physiologist to determine is, whe- 
ther, in the various races of mankind, the brain 
exhibits any striking peculiarities, characteristic 
of one or more of them, or whether it presents 
no more variety of shape, size, weight, and 
structure than may be observed in different in- 
dividuals of any one of those races. 
It should be premised that actual observa- 
tions of the brain of different races are few. 
In Europe, where hitherto anatomy has chiefly 
* Tiedemann on the Brain of the Negro com- 
pared with that of the European and the Orang 
Otang. Phil. Trans. 1836. 
+ Leuret, op. cit. p. 448. 
4 
