THE CEPHALINS 451 



as well as traces of ethanolamine and tartaric acids. The saturated fatty- 

 acids were composed of 5% cerebronic acid, and 95% of a mixture made up 

 of 70% palmitic acid and 30% of stearic acid. On the other hand, when 

 alkaline hydrolysis was employed, a non-reducing carbohydrate was pre- 

 pared which was shown to yield galactose after mild hydrolysis. The tar- 

 taric acid was found to be a d-isomer, while the molecular ratios of galac- 

 tose, inositol, and tartaric acid were in the proportions of 1:1:1. A sum- 

 mary of the constituents of lipositol as determined by analysis and by iso- 

 lation is given in Table 8. The fact that the components identified repre- 

 sent the major portion of all constituents present in the molecule is indi- 

 cated by the finding that they account for 102% of the lipositol, whereas a 

 theoretical recovery would amount to 109%. 



Table 8 

 Constituents of Soybean Lipositol" 



" D. W. Woolley, J. Biol. Chem., 147, 581-591 (1943). 



The structural relationships of the inositol phosphatide may, to a consid- 

 erable extent, be deduced from its partial hydrolysis products. The fact 

 that inositol monophosphate results from partial hydrolysis with acid, as 

 also proved earlier by Klenk and Sakai,^"^ is convincing proof that the phos- 

 phate is bound to the inositol in such a molecule. Since a non-reducing car- 

 Ijohydrate is formed on alkaline hydrolysis while a reducing sugar is set 

 free on subsequent acid hydrolysis, there is cogent evidence that the sugar, 

 which is galactose, is present in galactoside linkage. After assessing the ex- 

 perimental evidence as to whether tartaric acid or inositol is involved in this 

 galactoside combination, Woolley^"* came to the conclusion that it must be 

 the latter. Since free ethanolamine and free tartaric acid were liberated 

 only after alkaline hydrolysis, it was concluded that ethanolamine must be 

 present in the form of a tartrate. It is believed that, in lipositol, the sec- 

 ond carboxyl group of tartaric acid is esterified with inositol, although it 

 might also be joined with an alcohol group of galactose. In any event, if 

 tartaric acid is not combined with inositol, an oleic acid residue must be 

 united with this hexahydric alcohol, since at least three of the groups are 

 combined. These must be joined on alternate hydroxyls, as no two adja- 

 cent hydroxyl groups, of the six present, are free. 



There would thus seem to be considerable evidence for the supposition 



