NERVOUS SYSTEM. (Nervous Centres. Apnormat Anatomy.) 
in width. The white substance of the brain 
has increased in density, and in the transverse 
section several vessels are cut across, the sec- 
tion of which occasions numerous bloody 
— upon the surface of the centrum ovale. 
he corpora striata, optic thalami, pons, and 
medulla oblongataare all obviously shrunk and 
firm in consistence. 
In several instances of persons long bed- 
ridden, 1 have noticed a shrunk state of the 
cerebellum, with or without atrophy of the 
cerebrum. The layers of white matter in the 
cerebellar laminz look particularly small; and 
in the section the white layer seems to shrink in 
within the fold of grey matter in which it is 
involved. 
As a constant accompaniment of the wasted 
brain, we find a more or less opaque condition 
of the arachnoid membrane, with considerably 
enlarged Pacchionian bodies. The ventricles 
of the brain, too, are generally wide and con- 
_ tain a good deal of fluid. There is also very 
frequently a diseased state of arteries, atheroma- 
_ tous or ossific deposits being scattered freely 
amongst those, which form the circle of Willis, 
"and their principal branches. 
___ Atrophy of particular parts of the brain is of 
_ not unfrequent occurrence, either in cases where 
_ particular nerves are atrophied, as the optic 
_ nerve, inducing atrophy of the opposite optic 
tract or of that of the same side, and of the 
_ quadrigeminal bodies on the side of the wasted 
_ tract ; or where from previous disease of a por- 
_ tion of the brain the remainder of that part has 
| wasted—as wasting of thecorpus striatum from 
| the previous existence of a small clot in it, or of 
a red softening. 
| _ Softening. — One of the most common 
changes of structure in the brain is softening. 
| This is of two kinds, namely, white softening, 
or that without discoloration, and red softening, 
| or that with discoloration. 
_ _ White softening. —The anatomical characters 
of the true white softening may be thus de- 
scribed. The diseased portion has diminished 
considerably in its consistence ; if it be gently 
Tubbed with the edge of a knife it becomes 
Obviously disturbed by an amount of friction 
which would produce no change upon the sur- 
face of a healthy brain; a stream of water di- 
Tected upon it, even with slight force, is suffi- 
tient to break it up and separate as well as 
‘Tupture its constituent fibres, while a similar 
Stream directed against a neighbouring healthy 
_— produces little or no effect upon it. 
‘When examined by the microscope, its consti- 
‘tuent fibres appear to have undergone no change 
but that of consistence; they exhibit vari- 
Cosities, more numerous than usual, nor can 
‘any products of inflammation, or any other ab- 
Normal material, be detected among them. The 
oodvessels are empty and pale. The colour 
is very commonly that of cream, sometimes a 
little more yellow. 
This form of softening occurs chiefly in old 
persons, in whom the arteries of the brain have 
een more or less ossified, or in whom the 
ssels leading to the seat of softening have 
been so diseased as materially to interrupt or 
VOL, III. 
720a 
diminish the quantity of blood flowing to the 
part. It has occurred after ligature of the 
common carotid artery, as must be inferred 
from the numerous cases of hemiplegic para- 
lysis after this operation, on the side opposite to 
that of the tied artery; and I have myself re- 
_corded a remarkable example in which it was 
produced throughout nearly the whole hemi- 
sphere of the brain by the plugging of the com- 
mon carotid artery by a dissecting aneurism.* 
Any condition of the arteries of the brain, or 
of the general system, which may impair the 
nutrition of the brain, is favourable to the pro- 
duction of this form of softening. I have seen 
instances of it after inveterate contamination 
of the system by lead, in house-painters, who 
have had epileptic seizures before death, chemi- 
cal examination shewing that the nervous mat- 
ter of the brain contained lead in considerable 
quantity. It also occurs in persons dead with 
cerebral symptoms, epilepsy, coma, &c., in 
Bright’s disease of the kidneys. 
This softening frequently surrounds apoplec- 
tic clots, and in such cases is most probably 
the precursor of the apoplectic effusion. Fre- 
quently small apoplexies are found throughout 
a patch of softening of this kind, and sometimes 
the effused blood is infiltrated throughout the 
softened part to a great extent, and puts on an 
appearance which has been likened by Rostan 
and many others to one of the ecchymosed spots 
which are seen in scurvy. 
A colourless softening is found in hydroce- 
phaloid brains. This is probably due to an 
arrest in the nutrition of the organ, in conse- 
quence of which that condition of it which be- 
longs to infancy (when a much larger quantity 
of water enters into its composition than in the 
later periods of life, and when the brain-sub- 
stance is naturally very soft) becomes unduly 
developed, and water accumulates in the sub- 
stance as well as in the cavities of the brain. 
The softening under these circumstances is 
generally seen most distinctly in the thin lamellar 
portions of the brain, such as the corpus cal- 
losum, the fornix, the Vieussenian valve, the 
anterior and middle commissures, the septum 
lucidum. These parts are so soft that unless 
the greatest care and gentleness are used in the 
removal of the brain they give way. The 
softening is not limited to these parts, although 
greatest in them; it is general throughout the 
brain. When, however, the hydrocephalic 
state has been very chronic, the substance of 
the hemispheres becomes condensed by the 
pressure from within the ventricles, and the 
water having thus been pressed out of it, it 
appears of a natural consistence, or even more 
dense than natural. ; 
In all the cases of general paralysis of the 
insane which I have examined, the consistence 
of the brain generally bas been considerably 
less than natural. There have also been marks 
of chronic disease of the arachnoid in various 
patches of opacity, which I am disposed to 
view rather as a deposit from an abnormal 
blood than as the result of what is called 
* Med. Chir. Trans, vol. xxvii- 
Q 7 ** 
