CHAP. X.] THE NERVOUS TISSUES. 445 



SECT. 8. THE INORGANIC CONSTITUENTS OF THE NERVOUS TISSUES. 



Brain is extremely poor in inorganic matters, though it is difficult 

 from the discrepant results of various writers to give reliable facts as 

 to the exact amount of these ; the estimates vary between 01 and 

 1 per cent, of the fresh brain. 



Not only are statements discrepant as to the total quantity 

 of brain ash, but also as to the relative amounts found in the white 

 and grey matters. It appears to be true that the ash of the grey 

 matter has an alkaline, whilst that of the white has an acid reaction. 



The following table exhibits the results of the analyses of the 

 mineral matters of brain made in Hoppe-Seyler's laboratory by 

 Geoghegan 1 . 



INORGANIC MATTERS CONTAINED IN 1000 PARTS OF BRAIN. 



(1) (2) (3) (4) 



Cl ..................... 1-20 0-430 1-320 T064 



P0 4 .................. 1-40 0956 2-016 1'392 



CO 3 .................. 0796 0-244 0'548 0'330 



S0 4 .................. 0-220 0-102 0-136 0132 



Fe PO ............ 0-010 0-096 0'098 0'032 



Ca ..................... 0-005 0-020 0'014 0'022 



Mg .................. 0-016 0-068 0-080 0'072 



K ..................... 1-630 0-580 1778 1-520 



Na .................. 1-000 0-450 1114 0780 



Total Ash.., 6-277 2'946 7'084 5'344 



SECT. 9. GENERAL SUMMARY SHEWING THE RESULTS OF QUANTITA- 

 TIVE ANALYSES OF BRAIN, SPINAL CORD AND NEKVES. 



1. Proportion of Water. 



The amount of water is much larger in grey than in white 

 matter, in early than adult life. The following are observations made 

 by Weisbach on the brains of men. 



PROPORTION OF WATER IN 100 PARTS. 



Age Age Age 



20 to 30 30 to 50 70 to 94 



White substance of brain 69'56 68-31 72-61 



Grey 83-36 83-60 8478 



Cerebellum 78'83 77'87 80'34 



PonsVarolii 73'46 72'55 7274 



Medulla oblongata 74'43 73'25 73'62 



In the foetus the brain contains between 87'9 and 92'6 per cent, of 

 water. 



1 Geoghegan, "Ueber die anorganischen Gehirnsalze." Zeitschr. f. phys. Chern., 

 Vol. i. p. 330. 



