OP THE NERVOUS SYSTEM IN GENERAL. 



There may exist defects of symmetry, and defects of pro- 

 portion between the different parts of the system. 



766. The consistence of the nervous system is sometimes 

 changed. Softening* is an alteration very frequent in a part 

 of the central nervous mass. The softened nervous substance 

 is sometimes so much so as to be almost liquid. Its colour is 

 sometimes milk white; at other times it is yellowish, rose 

 coloured, red, or brown. This alteration is met with in the 

 optic layers, in the corpora striata, in the hemispheres of the 

 brain, in the cerebellum, in the medulla oblongata, and even 

 in the spinal marrow. It gives rise, according to its seat, to 

 different derangements of the sensations, of the voluntary mo- 

 tions, and of the other functions of the nervous system. It is 

 often the result of an inflammation ; in some cases it appears 

 independently. 



The hardeningt of the nervous system has been observed by 

 Esquirol, and by S. Pinel, who has very well described it. 

 The hardened nervous tissue presents a compact mass, organic 

 in appearance ; it resembles in colour, consistence, and density, 

 the white of an egg much hardened by cooking; no blood- 

 vessels are perceptible ; it appears contracted. The hardening 

 appears to affect particularly the white substance. It has been 

 observed in the bodies of idiots, in the brain, cerebellum, and 

 spinal marrow, where it renders the fibrous disposition of the 

 white nervous substance very manifest. 



767. The nervous system is subject to many affections. J 

 the principal of which are, in the central mass, sanguineous 

 congestion with or without effusion ; inflammation and its va- 

 rious degrees; the different products of chronic affections, as 

 encysted abscesses, the production of tubercles, of schirrus, 

 of cancers, of fibrous tumours and osseous, of hydatids, and 

 of foreign bodies. The membranes which envelop the cen- 

 tral nervous mass are equally the frequent seat of sudden con- 

 gestions with sanguineous or serous extravasation, of acute in- 



* Rostan, Recherches sur k ramolUssement du cerveau, 2d. edition; Paris, 

 1823. 



f Pinel, jr. Recherches sur fendurcissementdu syslemenerveux; Paris, 1822. 

 $ Lallemant, Recherches Jlnat. path, sur Fenctphak et ses dependences. 



