NERVOUS SYSTEM. (Nervous Cenrres. Apynormat Anatomy.) 
substance and passing into the lateral ventricle 
of one side, and thence through the foramen of 
Monro into the lateral ventricle of the other 
side. The convolutions are the next most 
frequent seat of apoplexy, and after them 
either hemisphere of the cerebellum, and either 
crus cerebri. The pons, crus cerebri, crus 
cerebelli, are much less frequently affected by 
hemorrhage. These parts are denser in struc- 
ture and less freely supplied with blood, and, 
therefore, less prone to apoplectic effusion than 
those before mentioned. 
Cancer of the brain.—Cancer is occasion- 
ally, although very rarely, found affecting some 
part of the encephalon; most frequently it ex- 
tends into some portion of it from the meninges. 
Andral has given a good history of this 
diseased condition, founded upon the analysis 
of forty-three cases.* Of these, the hemispheres 
were the seat of the cancer in thirty-one, in five 
the cerebellum was affected, once the meso- 
cephale, three times the pituitary body, and 
_ three times the spinal cord. 
The number and size of the cancerous tu- 
_ mors are very various. The cancer may begin 
in the meninges, and attack the bone on the 
_ one hand and the brain on the other ; or it may 
be first developed in the substance of the 
_ hemisphere. When the disease is superficial 
_ the cranial walls may become extensively im- 
plicated. I have seen the greater part of the 
parietal bone implicated in a cancerous tumor. 
_Andral mentions a case in which the frontal 
_ and temporal bones were completely destroyed, 
and another in which the cancer, developed at 
the inferior surface of the brain, passed out 
through the foramina of the base of the cranium. 
Cerebral cancer is most frequently of the 
soft or fungoid kind, but sometimes it occurs 
in the form of small hard tumours, deposited 
in various parts of the brain, and separated 
| from the surrounding cerebral substance by a 
distinct membrane or capsule. Frequently it 
appears to be primary, or at least there seems 
no evident connection between it and any other 
“eancerous deposit situate elsewhere. Of An- 
dral’s forty cases only ten were associated with 
neer in other situations. 
Tubercle of the brain. —The anatomical 
‘characters of tubercle of the brain are very 
“definite. The colour is yellow, the more con- 
picuous by reason of the white or grey of the 
Surrounding cerebral texture; the consistence 
¢ . Its section affords a smooth and clean 
rface, but if broken up by the point of the 
nife, its texture appears to be minutely granu- 
ar. Sometimes this tubercular matter may be 
icked out of a very distinct capsule. The 
tubercles vary very much in size, sometimes as 
Small as a millet seed, frequently the size of a 
- i pea, or even as large as a filbert or a wal- 
nut, rarely much larger. 
The parts of the brain most frequently af- 
fected by tubercle are the cerebral hemispheres 
jand those of the cerebellum. The mesocephale 
be the medulla oblongata are rarely the seat 
of it. It is generally situated near the surface 
_ 
* Clin. Med., t. v., p. 633. 
72058 
or near some process of pia mater; conse- 
quently it is most commonly met with in the 
grey matter of the brain. 
Cerebral tubercle excites inflammation in the 
surrounding brain substance, which is then 
found in the state of red softening ; and some- 
times suppuration may be established, the 
tubercular matter being more or less broken 
down and diffused in the pus. It is thus that 
tubercles of the brain prove so destructive to 
life. They may remain quiescent and unde- 
tected and even unsuspected until someirritation, 
often propagated from the periphery, excites 
surrounding inflammation, which by reason of 
the presence of the foreign matter of the tuber- 
cle, is kept up, and refuses to yield to any 
measure of treatment. Cerebral tubercle exhi- 
bits no spontaneous tendency to soften, nor 
does it frequently degenerate into earthy con- 
cretions. 
Enitozoa—The entozoa found in the brain 
are the cysticercus cellulose, and the acephalo- 
cyst, with its denizen the echinococcus. Like 
tubercles, these are always placed near the vas- 
cular surface, and they may be said more 
properly to infest the pia mater than the sub- 
stance of the brain; by their growth, however, 
they encroach more or less upon it. The ani- 
mals sometimes die, and their containing cysts 
shrink up and become converted into earthy 
matter, forming calcareous tumors of variable 
size in the substance or on the surface of the 
brain. 
Morbid states of the ventricles of the brain. 
—The diseased conditions of the ventricles of 
the brain are referable, first, to the cavities 
themselves ; secondly, to their contents ; thirdly, 
to their lining membrane and to the choroid 
plexus. 
The most frequent morbid condition of the 
ventricles is a state of dilatation, which is always 
passive, being produced by the accumulation 
of water in it. This retention of fluid within 
these cavities appears to be a true dropsy, and 
is in most cases connected with an external 
meningeal inflammation in a strumous constitu- 
tion. It is in children that we most frequently 
meet with this dilatation of the ventricles, and 
in them it constitutes the disease called hydro- 
cephalus internus. In adults it occurs some- 
times, but extremely rarely. In the former, 
when the disease is of a very chronic nature, 
the fluid will accumulate to a very great extent, 
and enlarge not only the ventricles but the 
cranium itself to an enormous size. 
In persons in advanced age, in lunatics of 
long standing, and in old epileptics, we fre- 
quently see a dilated state of the ventricles 
from distension by water. This is always asso- 
ciated with a wasted state of the brain; this 
fluid, as well as the external fluid, serving to 
fill up the space from which the cerebral matter 
had receded. 
In all these cases the ventricles which expe- 
rience dilatation are the lateral ventricles, the 
third and the fourth. Ina very few instances the 
fifth ventricle has been found similarly dilated. 
The fluid contained in the ventricles is gene- 
rally a clear straw-coloured serum, varying in 
