866 METHYL L.EVO-INOSITOL IN A POISONOUS PLANT, 



which effects its cleavage and yields inositol again, in the free 

 state. Starkenstein's investigations show that the source of free 

 inositol in tissues is the pliytin, and that inositol is a decompo- 

 sition-product of the phosphoric acid metabolism in both plants 

 and animals."^ Indeed, much work has been done in elucidating 

 the conditions of this transformation on the side of the phosphoric 

 acid, but again, as to the inositol side, nothing is known. 



The few definite observations concerning the part played in 

 metabolism, by inositol, are here summarised : — 



1. In iin7'ipe seeds, inositol and quercitol accumulate just at 

 the time when the transport of carbohydrates to the fruit begins. 



2. As the fruit 7'ipens, Vohl observed that inositol and quercitol 

 disappear, and are changed into "phytin" (not carbohydrate). 



3. On the yerinination of the seeds, inositol again makes its 

 appearance, both when grown in the dark and in the light. 



4. During the metabolism of the growing ptmit, inositol disap- 

 pears gradually with the rest of the reserve-substances. 



Thus it comes in at the beginning and later passes out again, 

 without a clue to its precursors or katabolites. 



AVhen fed to animals, or injected into the blood-stream, inositol 

 is about three-fourths decomposed, and the remainder may be 

 recovered from the urine unchanged. Mayer injected large doses 

 into rabbits, and obtained, from the urine, racemic lactic acid. 

 It is likewise decomposed by fungi into butyric and lactic acids. 



This inactive inositol, which occurs so widely in fresh green 

 plants, has been shown by many workers to be present in much 

 larger quantities in young growing plants (and animals) than in 

 the adult forms. It almost entirely disappears from plants when 

 they are slowly dried. 



The esters of active inositol, on the other hand, do not vanish 

 on drying the plants. When we consider the great rarity of 

 their occurrence, and the fact that the active forms have never 

 been identified in nature as free inositol, it almost leads one to 

 assume for them a different origin. Such an origin would be 

 more in common with that of certain well known plant-con- 



* Biochem. Zeitschrift, xxx., 1911, 98. 



