n6 THE CHEMISTRY OF THE TISSUES AND ORGANS. 
Solids. — The solids may be divided into the following classes : — 
(a) Proteids. — These comprise a very considerable percentage of the 
solids, especially in the grey matter (over 50 per cent.). 
(b) Neurokeratin and nuclein. 
(c) Phosphorised constituents; especially protagon and lecithin. 
(d) Cerebrins.— Nitrogenous substances of unknown constitution. 
(e) Cholesterin. — Especially abundant in white matter. 
(/) Extractives. — Creatine, 1 xanthine, 2 liypoxanthine, 2 inosite, 3 lactic 
acid, 3 leucine, 3 uric acid, 3 and urea. 
(g) Gelatin and Fat. — From the adherent connective tissue. 
(h) Inorganic salts. — The total mineral matter varies according to 
different writers from 01 to 1 per cent. 
Geoghegan 4 gives the following figures in parts per thousand of 
brain : — 
Total ash 
2-9 to 7T 
Chlorine 
Potassium 
0-6 „ 1-7 
P0 4 
Sodium 
0-4 „ 1-1 
co 3 
Magnesium . 
0-0 „ 0-07 
so 4 
Calcium 
0-005 „ 0-02 
Fe(P0 4 ), 
0-4 to 1-2 
0-9 „ 2-0 
0-2 „ 07 
01 „ 0-2 
0-01 „ 009 
The grey matter is stated by Schlossberger to be richer in total ash 
than the white, but poorer in phosphates ; Petrowsky, on the other hand, 
found more phosphates in grey than in white matter. 
The following table gives some typical quantitative analyses which 
have been made of the proportion in which the principal solids occur in 
different nervous structures : — 
Portion of Nervous 
System. 
Grey matter of ox 
brain s 
AVhite matter of 
ox brain 5 
Spinal cord 6 
Human sciatic 
Proteids. 
55-37 
24-72 
23-8 
36-S 
Lecithin. 
17-21 
9-90 
32-5; 
Cholesterin 
ami Fat. 
18-68 
51-91 
Cerebrins. 
0-53 
955 
75-1 
12-25 
Neuro- 
keratin. 
Other 
Organic 
Matters. 
6-71 
3-34 
11-30 3-07 I 4-0 
Salts. 
1-45 
0-57 
1-1 
The quantitative work I 8 have done on this question may be sum- 
1 Midler, Ann. d. Chem., Leipzig, Bel. ciii. S. Ill; St'adeler, Journ. f. prakt. Chcm., 
Leipzig, Bd. lxxii. S. 256. 
2 Stadeler, Ann. d. Chcm., Leipzig, Bd. cxvi. S. 102 ; Scherer, ibid., Bd. cvii. 
S. 314. 
3 Midler, lor. cit. : see also Strecker, Ann. d. Chcm., Leipzig, Bd. cv. S. 316. 
4 Ztschr. f. physiol. Chcm., Strassburg, Bd. i. S. 330. 
5 Petrowsky, loc. cit. 
6 Moleschott, loc. cit. 
7 Josepbine Chevalier, Ztschr. f. physiol. Chcm., Strassburg, Bd. x. »S. 97. 
8 Halliburton, Journ. Physiol., Cambridge and Loudon, 1893, vol. xv. p. 90. 
