470 GENERAL ANATOMY. 



composed of white, semi-transparent globules; some of thcrn 

 equal in size to those which form the nucleus of the coloured 

 particles of the blood, others smaller, of a gelatinous sub- 

 stance, transparent and soluble in water, and of a liquid simi- 

 lar to the serum of the blood: the proportion of these three 

 parts, the globules, the gelatine, and the serum, as well as the 

 size of the globules, gives rise to the principal differences 

 which the nervous system presents. The gray substance pre- 

 sents few distinct fibres not globular, it is formed especially of 

 very small globules; the gelatinous substance, and the serous 

 liquid are' very abundant in it. The medullary substance of 

 the hemispheres of the brain and cerebellum contains fibres 

 formed of linear series of globules more distinct and more 

 abundant; the greater part of the component globules are of a 

 greater diameter: the gelatinous substance is more tenacious 

 and in less proportion than in the gray substance. The cor- 

 pus callosum and the medulla oblongata have especially the glo- 

 bules of mean diameter, the gelatinous substance and the 

 serum are more abundant than in the hemispheres, and the 

 first is less tenacious. In the nerves, globules of all diameters 

 are found united into fibres, and these into fascicles. The ge- 

 latinous matter in question is found again in the blood, where 

 it serves as a uniting medium between the particles of the co- 

 louring matter which surrounds the globules. 



H. M. Edwards is publishing* at the present moment mi- 

 croscopic observations, according to which the nervous sub- 

 stance of the encephalon, of the spinal marrow, and of the 

 nerves, in the four classes of vertebral animals, is composed of 

 microscopic globules, 1-300 of a millimetre in diameter, 

 united in series in such a manner as to form primitive fibres 

 of considerable length. 



I have verified these observations, the importance of which 

 is so much the greater, as similar globules, but arranged a 

 little differently, are found in all the tissues of animals. 



According to Carus, the nervous globules are disposed in 



la structure, clcmcntairc dcs principanx tissus organiquesdes 

 animuux: These ; Paris, 30 juillct 1823. 



