PROFESSOR TIEDEMANN ON THE BRAIN OF THE NEGRO. 
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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, IIaslam, 
Esquirol, and others have already observed this, which is also confirmed by my 
own researches. The brain of very talented men is remarkable, on the other hand, 
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. The 
weight of an adult varies from 100 to 800 lbs., and changes both in health and when 
under the influence of disease, depending in great measure on nutrition. The weight 
of the brain, although different in adults, remains generally the same, unaltered by 
the increase or diminution of the body. Thin persons have therefore, relative to the 
size of the body, a larger brain than stout people. 
From my researches I have drawn the following conclusions. 
1. The brain of a new-born child is relatively to the size of the body the largest ; 
the proportion is 1 : 6. 
2. The human brain is smaller in comparison to the body the nearer man ap- 
proaches to his full growth. In the second year the proportion 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, as 1:35 to 45. In lean persons the 
proportion is often as 1:22 to 27 ; in stout persons as 1:50 to 100, and more. 
3. Although Aristotle has remarked that the female brain is absolutely smaller 
than the male, it is nevertheless not relatively smaller compared 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 larger than the male, compared with the size of the body. 
The different degree of susceptibility and sensibility of the nervous system seems to 
depend on the relative size of the brain as compared with that of the body. Children 
and young people are more susceptible, irritable, and sensible than adults, and have 
a relatively larger brain. Thin persons are more susceptible than stout. In diseases 
which affect the nourishment of the body the susceptibility increases as the patients 
grow thinner. The susceptibility and sensibility decreases, on the other hand, with 
persons recovering from a long illness, gradually as they regain their strength. The 
degree of sensibility in animals is also in proportion to the size of the brain. Mam- 
malia and birds have a larger brain and are more susceptible than amphibious ani- 
mals and fishes. I propose to go into this subject on another occasion, as it would 
at present take me too far from my immediate object. 
* Haller (De Partium Corporis Humani praecipuarum Fabrica et Functionibus, t. viii. p. 16.) says, “Ego 
in puero sex annorum, pondus librarum 2, drachmarum 28 cum scr. reperi, quae ratio, cum aegre 50 libr. ejus- 
modi puer aequat, fuerit fere In Pozziano exemplo fuit proxime In Arleti altero fuit omnino 
in altero Vs-> et si cerebri pondus rotundo numero 4 libras expresseris, hominis vero adulti libris 140, circa -Pt 
calculus fere subsisted” 
Cuvier (Anat. Comparee, tom. ii.) says that the relative weight of brain is = 1 : 22 — 35. 
