ON THE HUMAN BRAIN. 
231 
The animal kingdom, to the conglomerate ganglion of him who 
preys upon and usurps dominion over all. The description of 
the nervous system in the Crustacea — the mollusca — the nau- 
tilus — fishes — amphibia — and birds, is given at considerable 
length, and illustrated by some beautiful and accurate engravings. 
His account of the brain of the sheep we transcribe, premising, 
however, to our readers, that although it is accurate and elabo- 
rate, the author professes to do little more than point out the 
approach to the human brain in this larger animal, compared 
with that of the rabbit, which he had just described. 
'‘The upper surface of the cerebral mass of the sheep presents only two 
divisions; — the cerebrum, consisting of two hemispheres as usual, and the ce- 
rebellum. The olfactory ganglia can no longer be seen in front of the he- 
mispheres, as in the rabbit, these last having here increased in size so much, 
as completely to cover and conceal them. The hemispheres are not only of 
larger relative dimensions, but their shape is altered: they have lost the py- 
riform character they presented in the rodent animal, and have assumed 
more of the oval form which they possessed in the human being. Their sur- 
face, instead of being smooth, is convoluted, looking exactly as if it were 
formed by the folding up of a soft but tenacious substance. The cerebel- 
lum is not much changed in appearance ; it is only somewhat larger in pro- 
portion to the cerebrum. 
“ The great transverse commissure has increased in accordance with the 
greater development of the hemispheres ; and when we divide it in the mid- 
dle and turn either half back, in order to expose the optic tubercles, the 
thalami and corpora striata, we find the latter appearing as if they were 
placed within a circumscribed cavity, so much have the hemispheres in- 
creased in size in every direction. The space which is left between the cor- 
pora striata and thalami, and the under surface of the hemispheres, has ac- 
tually been described in the human brain as if it were a cavity or chamber 
scooped out of the substance of the brain, under the name of lateral ventri- 
cle. The erroneousness of this description and of the views which have led 
to it must be evident to every one who has followed the gradual develop- 
ment of the hemispheres from before backwards. We find, in fact, that the 
spaces denominated lateral ventricles are the necessary effect of the drawing 
back, if I may so express it, of those extensive surfaces of neurine covering the 
crura cerebri or anterior productions of the medulla oblongata. By the ad- 
dition of the anterior and posterior cerebral ganglia of the cord (the corpus 
striatum and thalamus), the structure comes to bear a considerable resem- 
blance to a head of cauliflower, included within its capsule of leaves ; or, as 
I have said elsewhere, to the nodulated head of a walking-stick, over and 
around which a piece of cloth has been tied, and then reflected forwards 
upon itself. 
“The edge of the fornix or longitudinal commissure may be seen lying in 
the groove between the anterior and posterior cerebral ganglia; the posterior 
ganglion or thalamus being however so completely covered, that it cannot 
be seen until the commissure is completely divided and reflected backwards. 
If, after doing this, the hemispheres be turned forward,|the cerebral ganglia 
on both sides will be exposed, with the pineal commissure and tubercula 
quadrigemina : crossing the fissure between the posterior cerebral ganglia 
(absurdly called the third ventricle), the commissura mollis or middle com- 
missure will be brought into view. 
