and rice polish. All of these preparations are said to be identical and 

 ail correspond to an acid having the following composition : C 12 H 41 O 42 P 

 or else inosite pentaphosphoric acid, L'oH^O^Pj. 



It is very evident from this resume that there is still great con- 

 fusion in the minds of the investigators who are working on this sub- 

 ject as to the actual composition of the inosite phosphoric acid. 

 Nearly every one who embarks upon an investigation in this field 

 reports entirely different results from any predecessor. This condition 

 merely emphasizes the difficulty encountered in purifying the prepara- 

 tions which are isolated. Further complications that arise are due to 

 the fact that the substance originally present in the plant material may 

 undergo changes of various kinds during the process of isolation. It 

 may suffer partial hydrolysis through the activity of the enzyme 

 (phytase) contained in the material itself or such partial hydrolysis 

 may be caused by the reagents or processes employed in the purifica- 

 tion ; the final product which is obtained may represent, therefore, not 

 the substance as it existed in the plant, but a mixture of such frag- 

 ments of the molecules of the inosite phosphoric acid as escaped either 

 the action of the enzymes or the more or less drastic action of the 

 reagents. The fact that the same investigator has produced appar- 

 ently identical results from a number of different materials is not 

 necessarily a sign of the purity of the preparations; being isolated by 

 identical methods, the same errors are carried over. As an example of 

 this kind of error we need only mention the fact that we (Anderson 

 1912, (3) 1914 (5) ) were unable to obtain any inosite phosphoric acid 

 having the composition of inosite hexaphosphoric acid from a 0.2 per 

 cent, hydrochloric acid extract of wheat bran. Instead of inosite hexa- 

 phosphoric acid we obtained consistently an amorphous barium salt 

 corresponding to the formula, C 20 H 45 O 49 P 9 Ba 5 , which on hydrolysis 

 gave inosite and phosphoric acid. This compound was obtained re- 

 peatedly and we were entirely unable to isolate a substance having any 

 other composition. Continued experiments with this compound 

 showed, however, that it was not homogeneous but that it could be 

 separated into various fractions and finally a substance was obtained 

 from this compound which corresponded in composition to inosite tri- 

 phosphoric acid, C 6 H 15 15 P 3 . The original substance was therefore 

 undoubtedly a mixture of inosite di- and tri-phosphoric acids with pos- 

 sibly some other admixtures. The extracts obtained on digesting 

 ground seeds, bran or other plant material in dilute acid contain a 

 large number of soluble constituents in addition to the phosphorus 

 compounds. It contains among others, also, soluble carbohydrates, 

 such as pentoses which are carried down in the precipitates of the 

 inosite phosphoric acids. Levene (1909), for instance, noted a pentose 

 in the preparation which he analyzed. In the barium salt prepared 



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