CHEMICAL BASIS OF THE ANIMAL BODY. 895 



glycerin-phosphoric acid being replaced by the radicle of stearic acid. It appears 

 also that there probably exist other analogous compounds in which the radicles of 

 oleic and palmitic acids take part. 



Preparation. Usually from the yolk of egg, where it occurs in union with 

 vitellin. Its isolation is complicated, and the reader is referred to Hoppe-Seyler. l 



Glycerin -phosphoric Acid. C 3 H 9 P0 6 . 



Occurs as a product of the decomposition of lecithin, and hence is found in those 

 tissues and fluids in which this latter is present ; in leukaemia the urine is said to 

 contain this substance. It has not been obtained in the solid form. It has been 

 produced synthetically by heating glycerin and glacial phosphoric acid ; it may be 

 regarded as formed by the union of one molecule of glycerin with one of phosphoric 

 acid, with elimination of one molecule of water. It is a dibasic acid ; its salts with 

 barium and calcium are insoluble in alcohol, soluble in cold water. Solutions of its 

 salts are precipitated by lead acetate. 



Protagon. (C 160 H 308 N 5 P0 35 ?) 



A crystalline body containing nitrogen and phosphorus, obtained by Liebreich 2 

 from the brain substance and regarded by him as its principal constituent. The 

 researches of Hoppe-Seyler and Diakonow tended to show that protagon was 

 merely a mixture of lecithin and cerebrin. A repetition of Liebreich's experiments 

 has, liowever, led Gamgee and Blankenhorn 3 to confirm the truth of his results. 

 Protagon appears to separate out from warm alcohol on gradual cooling in the form 

 of very small needles, often arranged in groups ; it is slightly soluble in cold, more 

 soluble in hot alcohol, and ether. It is insoluble in water, but swells up and forms 

 a gelatinous mass. It melts at 200 C. , and forms a brown syrupy fluid. 



Preparation. Finely divided brain substance, freed from blood and connective 

 tissue, is digested at 45 C. with alcohol (85 percent.) as long as the alcohol extracts 

 anything from it. The protagon which separates out from the filtrate is well 

 washed with ether to get rid of all cholesterin and other bodies soluble in ether, 

 and finally purified by repeated crystallization from warm alcohol. 



Neurin (Cholin). C 3 H 15 N0 2 . 



Discovered by Strecker 4 in pig's gall, then in ox-gall. It does not occur in the 

 free state except as a product of the decomposition of lecithin. It is a colorless 

 fluid, of oily consistence, possesses a strong alkaline reaction, and forms with acids 

 very deliquescent salts. The salts with hydrochloric acid and the chlorides of 

 platinum and gold are the most important. 



Neurin is a most unstable body, mere heating of its aqueous solution sufficing to 

 split it up into glycol, trimethylamin and ethylene oxide. 



Preparation. From yoke of egg. For this see Diakonow. 5 



Wurtze has obtained it synthetically, first by the action of glycol hydrochloride on trimethyl- 

 amin, and then by that of ethylene oxide and water on the same substance. The above, together 

 with the mode of its decomposition, point to the idea that neurin may be regarded as trimethyl- 

 oxyethyl-ammonium hydrate, N(CH 3 )3(C2H 5 O)OH. 



Cerebrin. C 17 H 33 N0 3 (?). 



Is found in the axis-cylinder of nerves, in pus-corpuscles, and largely in the 

 brain. In former times many names were given to the substance when in an 

 impure state, e. </., cerebric acid, cerebrote, etc. W. Miiller 7 first prepared it in 

 the pure form, and constructed the above formula from his analysis ; the mean of 

 these is 0, 15.85 ; H, 11.2 ; N, 4.5 ; C, 68.45. Great doubts are, however, thrown 

 upon its purity by the researches of later observers. According to Liebreich 8 and 

 Diakonow, 9 it is a glucoside. 10 



1 Med.-Chem. Untersuch., Heft ii. (1867), S. 215. 



2 Ann. d. Chem. \i. Pharm., Bd. cxxxiv., S. 29. 



3Zeitschr. f. physiol. Chem., Bd. iii. (1879), S. 260, and Journ. of Physiol., vol. ii. (1879), p. 113. 

 * Ann. d. Chem. u. Pharm., Bd. cxxiii., S. 353 ; Bd. cxlviii., S. 76. ' 



6 Op. cit. (sub. Lecithin). Ann. d. Chem. u. Pharm., Sup. Bd. vi., S. 116 u. 127. 



7 Ann. d. Chem. u. Pharm., Bd. cv., S. 361. 



8 Arch. f. pathoi. Anat., Bd. xxxix. (1867). 

 "Centrallb. f. d. med. Wiss., 1868, No. 7. 



10 See also Geogheghan, Zeitschr. f. physiol. Chem., Bd. iii. (1879), S. 332. 



