244 ANIMAL FATS AND PHOSPHATIDES. 



The same also applies to the claims as to the quantity of lecithin, 

 in various organs and tissues as well as in different ages. In these cases 

 the lecithin has not been prepared in a pure state, and the determina- 

 tions represent only the approximate quantity of phosphatides. These 

 determinations of SIWERTZOW, GLIKIN and NERKiNG, 1 show that lecithins 

 (phosphatides) occur abundantly in the bone marrow, suprarenal capsule, 

 heart and lungs, besides in the spinal marrow, brain, and egg, and also 

 that the quantity varies strikingly in different varieties of animals. 

 NERKING found 41.7 per cent lecithin in the bone marrow and 21.33 

 per cent in the suprarenal capsule of the sea-urchin when calculated on 

 the living organs, while the corresponding results in the rabbit were 2.71 

 and 2.39 per cent, respectively. 



The statements as to the properties of the lecithins apply chiefly to 

 the lecithin of the hen's egg, which since HOPPE-SEYLER and DIACONOW'S 

 time has been considered as distearyl-lecithin without any positive founda- 

 tion. Other lecithin preparations correspond essentially with this, and 

 certain differences between the various lecithins may be possibly due 

 to decomposition products or to admixture with other phosphatides. 

 It is still questioned whether the so-called distearyl-lecithin is a unit 

 body or not. 



Lecithin may be obtained in grains or warty masses composed of small 

 crystalline plates by thoroughly cooling its solution in strong alcohol. In 

 the dry state it has a waxy appearance, is plastic, but forms pulverizable 

 masses when dried in vacuum, and is soluble in alcohol, especially on 

 heating (to 40-50 C.) ; it is less soluble in ether. It is dissolved also by 

 chloroform, carbon disulphide, benzene, and fatty oils. The solution 

 of lecithin from egg-yolk is dextrorotatory (ULPiANi 2 ). P. MAYER S 

 claims to have prepared racemic lecithin from ordinary lecithin, and 

 Z-lecithin from the r-lecithin by cleavage with lipase. As he did not 

 make use of pure lecithin it is difficult to judge his- results. The solu- 

 tion of lecithin in alcohol-ether or chloroform is precipitated by acetone, 

 although not completely. It swells in water to a pasty mass which shows 

 under the microscope slimy, oily drops and threads, so-called myelin 

 forms (see Chapter XI). On warming this swollen mass or the concen- 

 trated alcoholic solution, decomposition takes place with the produc- 

 tion of a brown color. On allowing the solution or the swollen mass to 

 stand, decomposition takes place and the reaction becomes acid. Accord- 

 ing to the investigations of LONG 4 the lecithins seem to be much more 



1 Siwertzow, see Biochem. Zeitschr., 2, p. 310; Glikin, Biochem. Zeitschr., 4 and 

 7; Nerking, ibid., 10. 



2 Chem. Centralbl, 1901, 2, 30 and 193. 



3 Biochem. Zeitschr., 1. 



4 Journ. of Amer. chem. Soc., 30, 1908. 



