nS THE CHEMISTRY OF THE TISSUES AND ORGANS. 
ally in the grey matter, has been already alluded to. Petrowsky, in 
the investigation just mentioned, describes a globulin somewhat 
resembling myosin, and an albumin especially abundant in grey matter 
which is coagulated at a temperature of 75° C. Baumstark, 1 in a more 
recent research, speaks of the chief proteid matter in nervous tissue as 
resembling casein; this is so, for it is a nucleo-proteid. My own con- 
clusions 2 on the subject are as follows : — 
The proteids present arc three in number. The first is a globulin, 
coagulated by heat at 47° C, and analogous to the cell globulin deriv- 
able from nearly all cellular tissues. The second and most abundant is 
nucleo-proteid. In a saline extract of nervous tissues it is mixed with 
the other proteids; attempts to prepare it by the sodium-chloride 
method failed. It may, however, be prepared in large quantities by 
precipitating an aqueous extract of brain by weak acetic acid (Wool- 
dridge's method). The supply obtainable from white matter is small. It 
is coagulated at 56°-60° C. ; it contains 0*5 per cent, of phosphorus, and 
gives the general reactions of nucleo-proteids, production of intravascular 
coagulation included. The third proteid is a globulin, coagulated by 
heal at 70°-7f>° C, and analogous to a similar globulin separable from 
liver cells (see p. 8G). Peptone, proteose, myosin, and albumin are not 
obtainable. 
Protagon. — In the year 1865, Liebreiclr' separated from the bin in 
a material he called protagon ; he further found that, when decomposed 
by baryta water, it yielded two acids — stearic acid and glycero-phosphoric 
acid — and a base choline. 
Hoppe-Seyler, and Diaconow 4 working under Hoppe-Seyler's direc- 
tion, denied the existence of this substance, and considered that it was a 
mere mechanical mixture of lecithin with a nitrogenous non-phosphor - 
ised substance called cerebrin. Diaconow's analyses were, however, far 
from convincing. 
The subject was taken up in this country by Gamgee and 
Blankenhorn, 5 who showed that protagon is a perfectly definite 
crystalline substance of constant elementary composition. They also 
showed that even prolonged treatment with alcohol and ether will not 
extract lecithin from protagon, as alleged by Diaconow. When protagon 
is digested with alkalis it yields cerebrin or cerebrins, and the decom- 
position products of lecithin. This work has been confirmed by 
Baumstark, 6 Euppel, 7 and Kossel and Freytag. 8 
Protagon is prepared as follows: — The brain is digested with alcohol 
at 45° C. : the extract is filtered warm, and cooled to 0° C. It then 
deposits a white precipitate of protagon mixed with cholesterin, which 
is dissolved out by means of ether. The protagon is dried, redissolved 
in warm alcohol, and crystallises out on cooling. The empirical formula, 
calculated from their analytical results, is given as ( '^ll.^N-PO.,. by 
( iamgee and Blankenhorn. 
1 Ztsdhr. f. physiol. Ghent., Strassburg, Bd. ix. S. 145. 
- Journ. Physiol., Cambridge and London, 1893, vol. xv. p. 100. 
3 Ann. d. Chem., Leipzig, Bd. oxxxiv. S. 29. 
4 Centralbl.f. d. mcd. Wissensch., Berlin, 186S, S. 97. 
B Journ. Physiol., Cambridge and London, vol. ii. p. 113: Gamgee's "Physiol. Chem.," 
vol. i. p. 127. 
"> Ztsdhr. f. physiol. Chem., Strassburg, Bd. ix. S. 329. 
7 Ztschr. f. Biol., Mtinchen, Bd. xxxi. S. 86. 
8 Ztschr. /'. physiol. Chem.., Strassburg, Bd. xvji. S. 431, 
