NERVOUS SYSTEM. (Nervous Centres. Asnormat ANATOMY.) 
indicating a feeble developement of the insula 
of Reil. 
A few fissures and imperfectly developed 
convolutions were found upon the inferior sur- 
face of the middle lobe, as well as upon the 
lateral and inferior surfaces of the anterior lobe. 
The olfactory fissures were perfect but very 
small; the olfactory nerves appeared natural. 
The optic nerves were natural but small. 
The tuber cinereum was large and well 
developed. 
The corpora mamillaria appeared to be fused 
together along the median line. 
The pons Varolii very narrow from before 
backwards; the groove which passes along its 
middle was imperfect. 
The corpus striatum was exceedingly small, 
and the groove between it and the optic thala- 
mus was greatly increased in size. The tenia 
semicircularis was large. 
The convolution of the corpus callosum was 
_ very imperfectly developed. The hippocampus 
_ Major was very smal), and there could scarcely 
_ be said to be any trace of the hippocampus minor. 
_ _ The fornix was well developed, as was also 
the corpus callosum. The longitudinal tracts 
_ on the surface of the corpus callosum were also 
well developed. 
The pineal gland was large and situate very 
far forwards, corresponding very nearly to the 
_ middle of the optic thalamus. The quadri- 
_ geminal tubercles seemed imperfectly deve- 
loped, and the distinction between them was 
badly marked. 
_ The optic tract was small, but natural in its 
connections. The cerebellum was well deve- 
_ loped: its laminz seemed natural. The lateral 
| ventricles were large and rather dilated. The 
entire brain, after having lain in spirits for some 
days, weighed 1 Ib. 4} oz. avoirdupois. 
4 In some instances the hemispheres of the 
brain are fused together, there being little or 
‘no trace of a longitudinal fissure to separate 
them. This condition occurs generally in the 
Cyclopic monsters, or in monsters in which 
‘there is a total absence of the organs of vision. 
here there is this singleness of brain there is 
also sometimes a fusion of the corpora striata 
and optic thalami of opposite sides together. 
_ A total absence of all the transverse com- 
missures of the brain constitutes, as Rokitansky 
‘observes, the opposite condition to that just 
detailed. 
Idiotey results from any change which im- 
— to a material extent the structure of the 
hemispheres of the brain and of the fibres by 
) which they are connected to each other, as well 
} recorded instances of dissections of the brains 
. of idiots shew that the evil consists in such an 
pecan of the hemispheres and their con- 
) voluted surface as must have materially pre- 
vented their proper action. This may have 
begun in intra-uterine life or in infancy. The 
brain of infants at birth is far from being fully 
formed, and that part of it which is imperfectly 
developed is that upon which depends the mani- 
festation of mental actions, namely, the hemi- 
spheres of the brain and of the cerebellum ; the 
} as to the other parts of the encephalon. All the’ 
719 
other parts, which are mostly concerned in phy- 
sical nervous actions, are sufficiently perfect, 
being, however, generally small from the in- 
fluence of the deficiency of the hemispheres. 
Hypertrophy of the brain would occasion 
idiotcy, just as well as atrophy or imperfect 
developement of that organ (agenesie). Well- 
marked cases of idiotcy resulting from the 
former cause are, however, as far as I know, yet 
wanting in medical records. 
When there is a deficiency in any part of the 
cranial wall, a protrusion of a greater or less 
portion of the brain takes place—this consti- 
tutes hernia cerebri or encephalocele. It is in 
point of size proportionate to the size of the 
opening in the cranium. The tumour is co- 
vered externally. by the common integuments, 
and the displaced portion of the brain pushes 
before it the dura mater and the other mem- 
branes of the brain. 
The most frequent situation for hernia cerebri 
is in the occipital region of the head near the 
middle line, and next in point of frequency 
somewhere on the median line, where the bones 
of opposite sides remain for so long a time 
disunited: near the great fontanelle is a fre- 
quent site of a protrusion; sometimes it takes 
place on the side of the skull in the temporal 
region, or at the root of the nose. Such cases, 
however, are rare. 
2. Morbid conditions of the brain —Hy- 
pertrophy.— The examples of hypertrophy 
of the brain which are on record are not 
numerous, and it is difficult to attribute the 
appearances, which are said to indicate this | 
condition, to a mere increase in the nutrition 
of the organ. Adopting the term, however, in 
deference to the high authorities who have ap- 
plied it, it may be stated that the anatomical 
characters of a hypertrophic brain are as fol- 
lows :— 
The brain appears too large for the skull; 
on the removal of the calvaria the dura mater 
seems perfectly tense and filled by the brain ; 
it appears thinner and more transparent than is 
quite normal, and there is no trace of fluid in 
the subarachnoid space. 
The hemispheres are large, and their convo- 
lutions lie closely packed beside each other, 
and flattened. The ventricles of the brain are 
small, exhibiting the same condition as the 
fissures between the convolutions. The surface 
of the arachnoid as well as of the intra-ventri- 
cular eminences is dry or nearly so. 
The substance of the brain is universally 
firm, and cuts somewhat like cartilage ; it is 
exsangueous, the principal accumulation of 
blood being in the pia mater. The colour of 
the grey matter becomes so changed as to be 
scarcely different from the white. 
It is as yet uncertain what is the precise 
change which the brain undergoes in this con- 
dition. We know that there is an increase of 
substance, but whether that be an increase in 
the normal size of the fibres and vesicles of the 
two varieties of nervous matter which are found 
in the brain, or in their number, or whether it 
be a deposition of new material, with or with- 
out increase in the size or number of the ele- 
