236 ANIMAL FATS AND PHOSPHATIDES. 



in development. The new born come into the world with a store of phos- 

 phatides which dimir.ishes during growth. 



That the lecithins are of great importance in the development and 

 growth of living organisms, in fact for the bioplastic processes in general, 

 follows also from several investigations. 1 We have in lecithin or the 

 phosphatides as a group, no doubt, very important material for the build- 

 ing up of the complicated phosphorized nuclein substances of the cell 

 and cell nucleus. The wide distribution of the lecithins, as also the fact 

 that they are primary cell constituents, gives great importance to these 

 substances. 



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 3 

 claims to have prepared racemic lecithin from ordinary lecithin, and l- 

 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 XII). On warming this swollen mass or the concentrated 

 alcoholic solution, decomposition takes place with the production of a 

 brown color. On allowing the solution or the swollen mass to stand, 

 decomposition takes place and the reaction becomes acid. According 

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



1 See Stoklasa, Ber. d. deutsch. chem. Gesellsch., 29; Wiener Sitzungsber., 104; 

 Zeitschr. f. physiol. Chem., 25; W. Danilewsky, Compt. rend., 121 and 123, and W. 

 Koch, Zeitschr. f. physiol. Chem., 37; P. Kyes, ibid., 41, and Berl. klin. Wochenschr., 

 1904. 



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



3 Biochem. Zeitschr., 1. 



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



