NERVOUS SYSTEM. (NERVOUS CENTRES. ABNORMAL ANATOMY.) 720A 



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 

 points upon the surface of the centrum ovale. 

 The 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 laminae 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 

 rubbed 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- 

 rected upon it, even with slight force, is suffi- 

 cient to break it up and separate as well as 

 rupture its constituent fibres, while a similar 

 stream directed against a neighbouring healthy- 

 portion 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 

 bloodvessels 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 

 been more or less ossified, or in whom the 

 vessels leading to the seat of softening have 

 been so diseased as materially to interrupt or 



VOL. III. 



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 has been considerably 

 less than natural. There have also been marks 

 of chronic disease of the arachnoid in various 

 patches of opacity, which 1 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. 

 2 z ** 



