NERVOUS SYSTEM. (NERVOUS MATTER.) 



587 



stance of extreme softness and delicacy, liable 

 to break up under the least pressure ; the 

 nervous tissue owes much of its physical tena- 

 city to the other tissues which are associated 

 with it, and to the numerous bloodvessels 

 which play among its elements. 



The chemical composition of this matter has 

 been an object of investigation with several 

 observers, but it is remarkable that few com- 

 parative analyses of the two kinds of ner- 

 vous matter have been made with a view to 

 determine on what the differences between 

 them depend; and, indeed, such an analytical 

 investigation is as yet a great desideratum. 

 The part which has chiefly been selected for 

 analysis is the brain, in which doubtless both 

 kinds of nervous matter were indiscriminately 

 examined. 



Among the earliest investigations of this kind 

 were those of Leming; some time afterwards 

 Thouret examined the brain; and still later 

 Foim.Toy. The last writer notices the large 

 admixture of water with the cerebral substance, 

 and points it out as one of those animal sub- 

 stances in which water exists in the largest pro- 

 portion ; from constituting, as it does, three- 

 fourths or four-fifths, and in many instances 

 seven-eighths of its weight. Vauquelin's ana- 

 lysis, made in 1812, gave a considerable insight 

 into the true composition of the brain. This 

 chemist showed that the cerebral substance is 

 an emulsive mixture of albumen, fatty matter, 

 and of water, the last holding in solution certain 

 saline and other ingredients common to the 

 brain with other parts of the body. By solu- 

 tion in boiling alcohol, Vauquelin was enabled 

 to obtain the two constituents of the fatty 

 substance, namely, the elaine and stearine 

 (margarine). Vauquelin also recognised the 

 presence of phosphorus in the brain. His ana- 

 lysis yielded the following result: 

 Albumen 7.00 



r~, IIP,. { stearine . .4 53 ) 



Cerebral fat . . . . ; , _[.... 5.23 



I elaine. . . .0.70 } 



Phosphorus 1 .50 



Osmazome 112 



Acids, salts, sulphur 515 



Water 80.00 



100.00 



John, who specially analysed the grey ner- 

 vous matter, states that it is deficient in fatty 

 matter, and that its albumen is less tenacious 

 than that of the white. And Lassaigne states 

 that the grey substance is deficient in white 

 fatty matter, but contains a greater proportion 

 of red, 3.7 per cent, being the amount con- 

 tained in the grey, and 0.9 per cent, in the 

 white.* 



Vauquelin remarks that the medulla oblon- 

 gata and the medulla spinalis have the same 

 composition as the brain, but contain a much 

 greater quantity of cerebral fat, with less albu- 

 men, osmazome, and water. 



M. Couerbe's elaborate analysis does not ap- 

 pear to be entitled to much confidence, since the 



* Valentin Rcpcrt. 1837, p. 186. 



compounds into which he resolved the cerebral 

 matter did not, on analysis, always present 

 the same composition. This variation of ele- 

 mentary constitution he attributed to physiolo- 

 gical differences in individuals. 



The latest and apparently the most complete 

 analysis of the brain is that by Fremy, pub- 

 lished in the Annales de Chimie for 1841. 

 In the main his results agree with those of 

 Vauquelin. 



He states that the cerebral mass is formed, 

 as had been already shown by Vauquelin, of 

 an albuminous matter containing a great quan- 

 tity of water, and which is found mixed with 

 a peculiar fatty matter; and that these different 

 substances exist in the following proportions, 

 seven parts of albumen, five parts of fatty 

 matter, and eighty parts of water. 



The chemical examination of the albuminous 

 matter yields nothing of importance. This sub- 

 stance is insoluble in water, in alcohol, and in 

 ether. M. Fremy 's principal care has been to 

 determine the composition of the fatty matter, 

 and this he has endeavoured to do by an ana- 

 lysis of the brain in different animals, but prin- 

 cipally in man. 



His method of proceeding is, to cut the brain 

 into small pieces, and to treat it with successive 

 portions of boiling alcohol, leaving them forsome 

 days in contact with the spirit. The object of 

 this is to remove from it its large quantity of 

 water, which interferes with the action of ether 

 upon it. The coagulated mass thus obtained 

 is submitted to pressure, is divided rapidly in 

 a mortar, and is then treated by ether, first cold 

 and subsequently hot; the resulting fluids when 

 submitted to distillation yield a viscid residue, 

 which is called the ethereal product. 



The principles which he extracts from the 

 brain by this method, are 1. a white sub- 

 stance called cerebric acid; 2. cliolesterine ; 



3. a peculiar fatty acid called oleophosphoric ; 



4. traces of elaine, margarine, and fatty acids. 

 These principles are not always found in an 

 isolated state ; for the cerebric acid is often 

 combined with soda or phosphate of lime; and 

 the oleophosphoric acid is commonly found in 

 the state of a salt of soda. 



Cerebric acid, when purified, is white, and is 

 in the form of crystalline grains. It dissolves 

 without residue in boiling alcohol, is almost 

 insoluble in cold ether, more soluble in boiling 

 ether. It has the remarkable property of swel- 

 ling up, like starch, in boiling water, but ap- 

 pears to be insoluble in that liquid. It enters 

 into fusion at a high temperature, approaching 

 closely that at which it is decomposed, and is 

 combustible. It contains no sulphur, but some 

 phosphorus. The result of its analysis by 

 Fremy is 66.7 per cent, of carbon, 10.6 of 

 hydrogen, 2.3 of nitrogen, 0.9 of phosphorus, 

 19.5 of oxygen. 



Oleophosphoric acid is separated from cere- 

 bric acid by its solubility in ether. It is still 

 accompanied by elaine and cliolesterine, which 

 are withdrawn from it by alcohol and ether. 

 This acid is of a viscid consistence, insoluble 

 in cold alcohol, but dissolving readily in boil- 

 ing alcohol ; it is insoluble in ether. Placed 



