314 NERVOUS SYSTEM. 



The Central Portion of the Nervous System is composed of 

 two kinds of the substance called Neurine, distinguished by 

 their colour and relative situation: one is improperly enough 

 called Medullary, (Substantia Medullaris,) but as the name is 

 now sanctioned by universal usage, it is impossible to dispense 

 with it. The other is called Cineritious, (Substantia Cinerea,) 

 with, perhaps, sufficient propriety, from its colour. They are 

 both of a soft pulpy consistence, and constitute the chief mass 

 of the brain and spinal marrow : some anatomists have desired 

 to add, from some slight distinction of colour, two other sub- 

 stances, a yellow and a black, but that seems unnecessary, and 

 has not been acknowledged. These substances differ from one 

 another in regard to their quantity, the medullary being more 

 abundant than the eincritious - r it is also harder, and receives 

 fewer vessels. But the atoms of both have the same elementary 

 form, that of globules united by a semi-fluid substance; the 

 shape of these globules, as well as their size and degree of 

 solidity, are not yet ascertained.* 



The Medullary Matter, when quite fresh and scraped in par- 

 ticular directions has a filamentous appearance, which may be 

 rendered still more distinct by hardening it in alcohol, in boiling 

 oil, in a solution of the neutral salts, or in diluted mineral acids, 

 If an attempt be then made to tear it, it will be immediately 

 perceived that the fibres separate in a fixed direction, arid in 

 no other. These fibres, when viewed with a microscope, seem 

 to consist of fibrillse too fine to admit of any rigid conclusions 

 in regard to their size; and which are, in some instances, pa- 

 rallel, in others, concentric, and in others, diverging or con- 

 verging.! 



The two substances are variously placed in different parts 

 of the nervous system : the surface of the cerebrum and of the 

 cerebellum is formed by the cineritious matter, and the interior 

 principally by medullary ; while the surface of the pons, of the 

 crura, and of the spinal marrow, is medullary, and their interior 

 cineritious. Again, in other points, they are intermixed. The 



* Sir Everard Home, and M. Bauer, Phil. Transactions. London, An. 1821. 

 Milne Edwards, Thesis on the Elementary Tissues of Animals. Paris, 1823. 



t See Lessons on Practical Anatomy, by W. E. Homer, for description ot 

 Brain according to Gall and Spurzheirn. 



