278 



PHYSIOLOGICAL CHEMISTRY. 



are removed, pressed, and repeatedly boiled with alcohol, which is 

 filtered while boiling hot. The impure cerebrin which separates 

 on cooling is freed from cholesterin and fat by means of ether, and 

 then purified by repeated solution in warm alcohol. According 

 to PARCUS, this repeated solution in alcohol is continued until no 

 gelatinous separation of homocerebrin or encephalin takes place. 



According to GEOGHEGAN'S method, the brain is first extracted 

 with cold alcohol and ether and then boiled with alcohol. The 

 precipitate which separates on the cooling of the alcoholic filtrate 

 is treated with ether and then boiled with baryta-water. The in- 

 soluble residue is purified by repeated solution in boiling alcohol. 



The cerebrin may also be obtained from other organs by em- 

 ploying the above methods. The quantitative estimation, when 

 such is desired, may be performed in the same way. 



Neuridin, C 5 Hi4N 2 , is a non-poisonous diamin discovered byBniEGER, and 

 which was obtained by him in the putrefaction of meat and gelatine. It 

 also occurs under physiological conditions in the brain, and as traces in the 

 yolk of the egg. 



Neuridin dissolves in water, and yields on boiling with alkalies a mixture of 

 dimethylamin and trimethylamin. It dissolves with difficulty in amyl-alcohol. 

 It is insoluble in ether or absolute alcohol. In the free state neuridin has a 

 peculiar odor, suggesting semen. With hydrochloric acid it gives a combi- 

 nation crystallizing in long needles. With platinic chloride or gold chloride 

 it gives crystallizable double combinations which are valuable in its prepara- 

 tion and detection. 



The so-called CORPUSCULA AMYLACEA, which occur on the upper surface 

 of the brain and in the pituitary gland, are colored more or less pure violet by 

 iodine and more blue by sulphuric acid and iodine. They consist, perhaps, 

 of the same substance as certain prostatic calculi, but they have not been, 

 closely investigated. 



Quantitative Composition of the Brain. The quantity of water is 

 greater in the gray than in the white substance, and greater in new- 

 born or young individuals than in grown ones. The brain of the 

 foetus contains 879-926 p. m. water. According to the observations 

 of WEISBACH, the amount of water in the several parts of the brain 

 (and in the medulla) varies at different ages. The following fig- 

 ures are in 1000 parts ; A for men and B for women. 



White substance of 



the brain 



Gray ditto 



Gyri 



Cerebellum 



Pons varoli 



Medulla oblongata . 



20-30 Years. 

 A. #? 



30-50 Years. 



50-70 Years. 



70-94 Years, 



695.6 

 833.6 

 784.7 

 788.3 

 734.6 

 744.3 



682.9 

 826.2 

 792.0 

 794.9 

 740.3 

 740.7 



6831 

 83fi.l 

 795.9 

 778.7 

 7255 

 732.5 



703.1 

 830.6 

 772.9 

 789.0 

 722.0 

 729.8 



A. 



701.9 



838.0 

 796.1 

 787.9 

 720.1 



722.4 



B. 



689.6 



838.4 

 796.9 

 784.5 

 714.0 

 730.6 



726.1 

 847.8 

 802.3 

 803.4 

 727.4 

 736.2 



722.0 

 889.5 

 801.7 

 797.9 

 724.4 

 736.7 



