n8 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 are 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 ("VVool- 

 dridge's method). The supply obtainable from white matter is small. It 

 is coagulated at 56-60 C. ; it contains O5 per cent, of phosphorus, and 

 gives the general reactions of nucleo-proteids, production of intra vascular 

 coagulation included. The third proteid is a globulin, coagulated by 

 heat at 70-75 C., and analogous to a similar globulin separable from 

 liver cells (see p. 86). Peptone, proteose, myosin, and albumin are not 

 obtainable. 



Protagon. In the year 1865, Liebreich 3 separated from the brain 

 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 Garngee 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 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 C 160 H 308 N 5 P0 35 by 

 Gamgee and Blankenhorn. 



1 Ztsclir. f. physiol. Chem., Strassburg, Bd. ix. S. 145. 



- Journ. ' Physiol., Cambridge and London, 1893, vol. xv. p. 100. 



3 Ann. d. Chem., Leipzig, Bd. cxxxiv. S. 29. 



4 Centralbl.f. d. med. Wissensch., Berlin, 1868, S. 97. 



5 Journ. Physiol., Cambridge and London, vol. ii. p. 113; Gamgee's "Physiol. Chem.," 

 vol. i. p. 427. 



6 Ztsclir. f. pliysiol. Chem., Strassburg, Bd. ix. S. 329. 



7 Ztschr.f. Biol., Miincheu, Bd. xxxi. S. 86. 



8 Ztschr. f. physiol. Chem., Strassburg, Bd. xvii. S. 431, 



