662 
mammalia.* This statement, although appli- 
cable to the encephalic mass when viewed as a 
whole, does not apply to certain of its parts, 
which are often more developed in the less 
perfect than in the more highly organized ani- 
mals. The cerebrum and cerebellum, however, 
exhibit this gradual increase of developement, 
and their enlargement is in accordance with a 
gradually increasing manifestation of mental fa- 
culties. And itis upon the great size of these 
that the superiority of the human brain 
over that of all other animals depends. 
In comparing the brains of some of the 
larger mammalia with that of man, we observe 
an evident want of correspondence between 
the bulk of the encephalic nerves and that of 
the encephalon itself. This does not accord 
with what we have had occasion to notice 
respecting the spinal cord, in which large 
nerves were always concomitant with high 
developement of the organ itself. The maximum 
weight, as Miiller remarks, of a horse’s brain is, 
according to Soemmering, 1 lb. 70z.; the mini- 
mum of an adult human brain 2 Ib. 54 oz.; and, 
nevertheless, the nerves at the base of the brain 
are ten times thicker in the horse than in the 
human subject. 
This want of correspondence between the 
developement of the mass of the body and that 
of the brain, as well as between the size of that 
organ and of the encephalic nerves, must surely 
be admitted to indicate an incorrectness in the 
assertion of the distinguished physiologist who 
has just been quoted, namely, that ‘ all the 
rimitive fibres of the nerves terminate in the 
rain; those of the cerebral nerves immediately, 
those of the spinal nerves through the medium 
of the spinal cord.”+ The human brain must 
evidently contain numerous other fibres besides 
those which are continuous with the roots of 
Taste I. 
Average weight of the encephalon, &c. between 25 and 55 years of age, in the two 
and the average difference between them—Males, 53 brains weighed—Females, 34 
weighed :— 
NERVOUS SYSTEM. (Nervous Cenrazs. Tae Enceruaton.) 
the nerves, and it is likely that the horse’s brain 
contains similar ones, although less numerous 
it seems, therefore, impossible that the small 
brain of the horse can be the point of con- 
vergence of the large spinal and cerebral nerves 
of that animal; and if this be true as regan 
the horse, it is so likewise in man. It isn uc 
more probable that a large proportion of them 
do not extend beyond the spinal cord, and tha 
the greater number of the fibres of the ene¢ 
phalic nerves do not go beyond the part i 
which they are immediately implanted. 
It must be admitted, however, that althou 
this disproportion is very manifest as regal 
the hele encephalon, it is hot so evident 
we compare the nerves with those segmen 
the organ from which they immediately ari 
Thus, the medulla oblongata is always, 4 
regards mere bulk, in the direct ratio of 1 
nerves ; the optic lobes are large when | 
optic nerves are so; the olfactory lobes t 
close relation to the number of the olfae 
nerves, and it may be added, to the complicati 
of the olfactory organ. It is to the cerebi 
hemispheres, to the cerebellum and the syster 
of fibres immediately connected with them 
we must attribute the oe rtion in questio 
those parts being smal we the nerves ; 
large, as in the horse, and large when the ner 
are of small size, as in man. 
The human encephalon weighs about 4 
for the male, and 44 oz. for the female.* 
estimate, which was formed by Krause, ¢ 
not differ very materially from that der 
from Professor phi Reid’s careful obse 
tions made at the Infirmary at 
burgh. The scllowine tables are extra 
from a paper by this excellent anatomist i 
London and Edinburgh Monthly Journ 
Medical Science for April, 1843. > 
% 
Male. Female. 
Ib. ox. dr. Ib. os. adr. 
Average weight of encephalon ...+++.... ; 3 . * ) Py bi Ps * 
Cerebrum eee Ce eee eeee ee eee eee eeeee 43 15% 38 12 
Cerebellum eee eee ee eee eee eee eT eee er eeee 5 4 4 12} 
Cerebellum, with pons & medulla oblongata 6 3% 5 12 
Taste II. a 
Relative weight of encephalon to cerebellum, and to cerebellum with medulla oblonga 
pons Varolii, between 25 and 55 years of age, in the two sexes (53 male and 34_ 
brains weighed). Male. 
Relative weight of encephalon to cerebellum........ coccse coe 281 to 
Ditto to ditto, with pons and medulla oblongata........... Te wo 
From this table it would appear that, inthe in the first table quoted. For this 
female, the average cerebellum is, relative tothe 253 brains were weighed. 
encephalon, a little heavier than in the male. 
In a third table, which has been reduced 
from that published by Professor Reid, the 
average weight of the encephalon, cerebellum, 
with pons Varolii and medulla oblongata, is 
given over a much wider range of age than that 
* See the table at p. 623 of this volume. 
t Physiol. trans], by Baly, 2nd ed. p. 796. 
* According to Mr. Hamilton’s investi 
the adult male brain in the Scot’s head weig 
an average, 3 Ibs. 8 oz. troy; about one’ 
seven is found about 4Ibs. troy; the e 
weighs 3 lbs. 4 0z.; and one of a hund 
brains weighs 4 Ibs. : 
t Reference may also be made to an_ 
series of observations on the weight of the 
by Dr, Sims, Med. Chir. Trans. vol, > | “ 
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