CHEMICAL BASIS OF THE ANIMAL BODY. 1239 



In accordance with these views the constitution of lecithin 

 may be most adequately represented by the following formula 



^(C n H 2n _i0 2 ) 2 



C 3 H 5\0 PO /OH 



u,ru \O.C 3 H 4 .(CH 3 ) 3 N.OH, 



where C n H 2 „ 1 2 represents the radicle of a fatty acid which 

 in ordinary lecithin appears to be that of stearic, viz. C 18 H 35 2 . 



Glycerinphosphoric acid. 



C 3 H 9 P0 6 . [C 3 H 5 .(OH) 2 .O.PO(OH) 2 ]. 



Occurs as a product of the decomposition of lecithin, and 

 hence is frequently found in those tissues and fluids in which 

 the latter is present. It may occur occasionally in urine. 



The acid is dibasic and forms salts which are usually, so 

 far as they are known, soluble in cold water, but the lead salt 

 is an exception to this rule and may hence be used as a precipi- 

 tant. The salts are insoluble in alcohol. 



Jecorin. This is a substance at first prepared from the liver 

 (whence its name), but subsequently from spleen, blood, muscles, 

 and brain. In its solubilities, etc., it resembles lecithin, and simi- 

 larly contains phosphorus, but unlike the latter it reduces Fehling's 

 fluid. Very little is yet known as to its composition and nature. 



Choline. C 5 H 15 N0 2 



(CH 3 ) 3 _ N \ CH2>C H 2 (OH) 



trimethyloxyethyl-ammonium hydroxide. 



Discovered originally among the products of the decomposi- 

 tion of pigs'-bile and subsequently of ox-bile, whence the name 

 choline. It does not occur in the free state except as a product 

 of the decomposition of lecithin, but has been recently obtained 

 in extracts of the suprarenals. 



Choline when pure is an oily liquid with a strong alkaline 

 reaction, soluble in alcohol or ether. It yields crystalline 

 compounds with acids and with some salts, of which the double 

 salts formed with hydrochloric acid and the chlorides of either 

 gold or platinum crystallize readily and are employed for the 

 detection and separation of the base. The platinum salt is 

 readily soluble in water, insoluble in alcohol. The gold salt 

 is but slightly soluble in cold water, but soluble in hot alcohol. 



When boiled in concentrated solution choline is decomposed 

 into glycol and trimethylamine 



(CH 3 ) 3 = N(gH C h 2(0 H) = C 2 H 4(OH) 2 + N(CH 3 ) 3 . 

 By oxidation with concentrated nitric acid it yields the 



