COMPOSITION OF NERVOUS MATTER. 



273 



More precise ideas would be arrived at regarding the waste of the nerv- 

 ous mechanism if we possessed a more accurate knowledge of its chem- 

 ical constitution. The examinations hitherto made are far ~ 



Composition of 



from agreeing with one another, and this, to a certain extent, nervous mate- 

 is due to the difficulty of obtaining the true nervous tissue in nal ' 

 an isolated state, or unmingled with other intervening structures. * The 

 following tables will give, however, a general idea of its composition at 

 different periods or in different conditions. 



Analysis of Brain of different Conditions of Life. (From L'Heritier.) 



Composition of Spinal Cord of Adult. (From L'Seritier.") 



Water 710.50 



Albumen 73.00 



Fat 82.50 



Osmazome 115.00 



Phosphorus 19.00 



1000.00 



Analysis of Medullary and Cortical Substance of Brain of Idiot. (From Lassaigne.) 



From which it would appear that the percentage of water is greatest in 

 the early periods of life, and that of phosphorus in the adult. Attention 

 may also be drawn to the fact that the percentage of phosphorus in the 

 brain of idiots is very low. It also appears that the constitution of the 

 white and gray portions of the brain is different, as might have been an- 

 ticipated from tlieir appearance, the color of the latter being due to a 

 brown fat. By some it is supposed that the non-saponifiable fat cho- 

 lesterine arises as a product of waste, and that the phosphorized oils, as 

 they are termed, constitute the white enveloping cylinder known as the 

 white substance of Schwann, and that the interior cylinder is a nitrogen- 

 ized but non-phosphorized body ; but there are reasons for suspecting 

 that the white substance of Schwann is a non-phosphorized fat, and that 

 .the axis cylinder contains the phosphorus in an unoxidized state, prob- 

 ably as a highly phosphorized protein body. Every thing seems to in- 



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