820 THE ROLE OF NITROGEN, ETC., I., 



present originally as hexoses or polysaccharoses, but it is an 

 interesting fact that, hitherto, we have known no carbohydrates 

 soluble in ether and almost insoluble in water. Their presence 

 in these complex phosphatides and in nucleic acid points to a 

 resemblance in constitution to jecorin, which Drechsel isolated 

 from the liver, and to the crystalline cerebrins from the brain, 

 and forms another relation between animal- and plant-chemistry. 



True lecithin, as an individual plant-constituent, was first 

 discovered in yeast in 1866 by Hoppe-Seyler,(62) who also recorded 

 the fact that both lecithin and cholesterin occur generally in 

 plant-seeds. 



When seeds are extracted with hot absolute alcohol, the whole 

 of the fat goes into solution together with waxes, lecithins, and 

 the phytosterols or plant-cholesterin. The solvent is distilled off, 

 and the residue extracted with ether which dissolves the lecithin 

 and leaves behind all other phosphorus-compounds. The amount 

 of phosphorus in the ether solution is estimated, and from this is 

 calculated the percentage of lecithin. Jacobson(63) has estimated 

 the amount of lecithin in a number of leguminous seeds, and tinds 

 that from 6 to 30 %of the fat is lecithin. Schulze obtained from 

 beans 1*64 %, from Lupinus luteus 1*5 %, and from Vicia sativa 

 1*22 % of lecithin in the dried seeds. 



The hydrolysis of lecithin, and also its synthesis, is generally 

 assumed to be brought about by the lipolytic ferments, the pro- 

 ducts of hydrolysis being chlorin, glycero-phosphoric acid, and 

 fatty acids. Rosenheim has shown that cholin is present in all 

 animal organs where there is great cell activity and tissue-disin- 

 tegration; it is also present in plant-tissues and seeds. The 

 various lecithins are distinguished by the particular fatty acids 

 in their composition, most plant-lecithins containing both saturated 

 and unsaturated acids, viz., stearic, palmitic, oleic, and linoleic. 

 According to Koch, the specific characters are due to the unsatu- 

 rated acids, and it may be that these convey the property of 

 linking on such organic compounds as carbohydrates, proteins, 

 glucosides, and alkaloids, which are known to combine readily 

 with lecithin. The first clue to the proper function of lecithin 



