OF THE NERVOUS SYSTEM IN GENERAL. 471 



clusters in the central masses which act by radiation, and in 

 regular lines in the nerves which act only as conductors. 



750. The cellular tissue, which unites the nervous fibrils, 

 is soft and little apparent. This tissue is more condensed at 

 the surface; where united with the vessels, it forms a mem- 

 brane, more or less dense, more or less vascular; single for 

 the nerves (neurilema), double about the nervous centre (pia 

 mater and dura mater), having an interval with contiguous 

 walls formed by a serous membrane (tunica arachnoides). 



751. The sanguineous vessels of the nervous system are 

 very numerous. They ramify very much in the immediate 

 envelope of this tissue (neurilema and pia mater); they after- 

 wards penetrate into the gray substance, where they are ex- 

 tremely abundant; they penetrate finally into the white sab- 

 stance, in which they are much finer and less numerous. No 

 lymphatic vessels have been discovered in the nervous sys- 

 tem. 



752. The nervous substance has been examined chemically 

 by Thouret, Fourcroy, and Vauquelin. 



The analysis of the brain by Vauquelin, has given the fol- 

 lowing results; water 80.00; white fatty matter 4.53; red- 

 dish fatty matter 0.70; albumen 7.00; osmazome 1.12; phos- 

 phorus 1.50; acids, salts and sulphur 5.15. 



According to the experiments of this able chemist, the 

 spinal marrow and the nerves have the same composition as 

 the brain. 



John has recognised that the gray substance contains no 

 phosphorus. 



Chevreul has found in the blood a substance characteristic of 

 the nervous matter, cerebrine. 



753. The vital properties of the nervous system distin- 

 guish it essentially from all other organs; besides the faculty, 

 common to all parts of living bodies, of nutrition, it possesses 

 another active property, altogether peculiar, which is called 

 nervous force, nervous power, nervous influence; manifests 

 itself by the functions of this system designated collectively 

 by the name of innervation. 

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