THE LECITHINS. 77 



(3) CH 2 .O.OigH 3 ijO (OH 3 ) 3 CH 2 .O.Gi 8 H 3 gO 



I ^ I 



CH.O.C 18 H 35 O + N CH 2 .CHO = CH.O.C 18 H 35 O 



CH 2 .0 PO(OH) 2 OH CH 2 .0 P0 2 .C 2 H 4 \ 



OH 



Cholin. 



Lecithin. 



On decomposition of the lecithins with acids or alkalies we 

 accordingly obtain glycerin-phosphoric acid, fatty acids, and cholin. 

 At the same time, however, another basic substance, neurin, is 

 usually found, and it is to be noted that, in contradistinction to 

 cholin, neurin possesses extremely toxic properties. It results from 

 cholin through the loss of two atoms of hydrogen and one atom 

 of oxygen, and is also formed during bacterial decomposition of 

 the lecithins in the presence of much oxygen. Chemically it is 



/(CH 3 ) 3 

 trimethyl-vinyl-ammonium hydroxide, N CH=CH 2 , while cholin 



\)H 

 must be regarded as trimethyl-oxyethyl-amrnonium hydroxide. 



Another derivative of cholin which may be obtained through the 

 action of fuming nitric acid is a basic substance that is apparently 

 isomeric with muscarin and, like this, extremely toxic. Chemically 



/CH S ) S 



it may possibly be represented by the formula N CH 2 .COH, and 



\OH 



could accordingly be regarded as the aldehyde of oxyneurin (tri- 

 methyl glycocoll). 



The lecithin which is most commonly found in the animal body 

 is the cholin compound of distearyl-glycerin-phosphoric acid ; other 

 lecithins can, of course, also occur, in which the glycerin hydroxyl 

 groups have been replaced by the radicles of oleic and palmitic acids, 

 for example, but they are but little known. 



In its dry state the common lecithin occurs as a wax-like, plastic 

 mass, which is soluble in alcohol (at 40-50 C.), ether (less readily), 

 chloroform, benzol, carbon disulphide, and in the fatty oils, while in 

 water it is insoluble. Placed in water it swells and becomes pasty, 

 and on microscopical examination it will be noted that the substance 

 occurs in the form of peculiar slimy droplets and threads, which are 

 generally termed myelin forms. From its alcoholic solution it 

 crystallizes in wart-like masses, which consist of small platelets. 



Of special interest is the tendency of the lecithins to combine with 

 albumins to form more or less stable compounds, which have been 

 termed lecithalbumins. Such compounds have been found in the 

 mucosa of the stomach, in the lungs, the liver, and the spleen. In 



