I9I2] Anton Richard Rose 35 



structure, is an open question. It is probably an ester of phosphoric 

 acid with inosite, in which six phosphoric acid groups are united 

 with each inosite molecule. This ratio, Cß : Pg, is indicated for the 

 vast majority of the pure preparations analyzed; exceptions are the 

 preparations by Levene, Vorbrodt and Rising (Table 2), these 

 authors giving the ratio Cq : P5.5. Anderson has pointed out that 

 bis and Rising's silver salts are probably identical, Rising's analysis 

 being equally well adapted to the formula C6Hi7027P6Ag7. It 

 seems probable that the molecular weight when accurately deter- 

 mined will be reported as 714 or will differ from this by the molec- 

 ular weight of three molecules of water, The molecule seems to 

 contain twelve hydrogen atoms readily separated in ionization, six of 

 which are exceedingly reactive ; the remaining hydrogen atoms 

 gradually diminish in reactivity by twos, the last four being slow 

 to enter into an exchange with bases. The most readily formed 

 salts are therefore those corresponding to an octavalent acid and the 

 other common ones are in six and tenvalent combinations. 



TERMINOLOGY AND CLASSIFICATION 



The investigations of which this paper is a brief review have 

 brought to the biological chemist and plant physiologist a type of 

 phosphorus Compound from the plant world which is relatively 

 new and probably of prime importance. The phosphorus which 

 occurs in acid and water extracts was formerly considered inor- 

 ganic phosphate, and awakened no especial interest, and the mention 

 of organic phosphorus immediately brought to mind nucleoproteins 

 and lecithins. In the organic laboratories combinations of phos- 

 phorus with various organic radicals have been made and recently- 

 prepared phosphoric acid esters'^ resemble " phytin " in some respects, 

 and so may be considered of special concern to the biological 

 chemist, as possibly bearing on problems in his field. A cleavage 

 product of inosinic acid, c?-arabinose phosphoric acid,^ is significant 

 as showing that carbohydrate esters are not confined to those pro- 

 duced by the synthetic Operations of the laboratory. Even more 



'v. Lebedew: Biochem. Zeit., 1909, 20, 114; Neuberg and his coworkers : 

 Ber., 43, 2060; Biochem. Zeit., 23, 515; 26, 115 and 529; 36, 5; Langheld, Ber., 44, 

 2076. 



'Levene and Jacobs, Ber., 191 1, 44, 746. 



