13 



whicli tlie fat must be clianged to become combustible in the proto- 

 plasm, since tlie substances serving for respiration, must be present in 

 tlie protoplasm in a dissolved condition.^ Since fat is not soluble, a 

 transformation of it into soap was formerly assumed — a view which is 

 hardly possible in the case of plants, while upon animals soaps injected 

 subcutaneously exert a poisonous action (Munk, 1889). 



By the transformation of fatty matter into lecithin the higher fatty 

 acids are offered to the protoplasm in a soluble form, and after being 

 oxidized other molecules of fatty acids may enter into the place of the 

 former and thus the same molecules of the glycerol-phosphoric acid can 

 serve repeatedly as vehicles for oxidations of molecules of fatty acids. 

 The fact that blood corpuscles contain lecithin, but not fat seems to 

 indicate that lecithin may be produced not only from fat, but also 

 directly from sugar, as is fat. A great therapeutic value of lecithin 

 has been demonstrated in cases of nervous debility and weakness of 

 the alimentary functions. The brain and the whole nervous system in 

 general ^re rich in lecithin, fully 17 x>ev cent of it having been found 

 in the gray substance of the brain. The nervous system requires for 

 its perpetual great activity a substance which unites easy combusti- 

 bility with a great deal of potential energy in a small volume, which 

 conditions are admirably united in the lecithin. 



Seeds rich in starch generally contain much less lecithin than those 

 rich in jirotein. Thus barley grains contain less than half the amount 

 contained in soy beans. The amount of lecithin increases to a certain 

 point in the first stages of germination, while the amount of fat 

 decreases.^ Here the lecithin is evidently formed from the fat. It 

 seems very probable that the observed increase of lecithin is less than 

 was actually formed, since a part of it is probably consumed nearly as 

 quickly as produced. The evergreen tea leaves lose the reserve lecithin 

 in spring (Hanai) and green plants generally lose it when kept in the 

 dark (Stoklasa). Heffter observed a decrease in the amount of lecithin 

 in the liver during starvation. E. Schulze ^ found that during germi- 

 nation the quantity of choline increases, and that in wheat the choline 

 is localized in the germ of the grain, but not in the endosperm. 

 This is certainly of physiological interest, since the young developing 

 germ must carry on an energetic respiration and therefore be capable 

 of easily forming lecithin, in which process the presence of choline is 

 required. It may further be mentioned in this connection that, accord- 

 ing to Miintz, the amount of free fatty acids increases during germina- 

 tion, which is to be expected when lecithin is formed from fat. From 



1 We can observe this with cholesterin, which is frequently contained in the cells 

 and in fact is, like lecithin, a constant concomitant of fatty matter. It is not per- 

 ceptibly oxidized by the protoplasm, the almost absolute insolubility in water being 

 here the obstacle. 



"Maxwell, Chem. Centralbl., Vol. XLI, No. 1, p. 365; Frankfurt, Landw. Vers. Stat., 

 Vol. XLIII. 



^ Landw. Vers. Stat. , Vol. XL VI. 



