ALCOHOLS IN PLANTS 387 



Of the polyhydric alcohols Inosite is of particular interest, 

 and may, therefore, receive more detailed consideration. 



INOSITE. 



Inosite, which has the formula CgH^gOg, is isomeric with 

 the hexoses, and, like these substances, has a sweet taste ; for 

 these reasons it was at one time thought to be a true sugar 

 and was called muscle sugar owing to its occurring in muscle. 



Inosite is, however, not a carbohydrate at all but a 

 polyhydric alcohol derived from benzene and having the 

 constitution — ■ 



CHOH— CHOH 



/ \ 



CHOH ^CHOH 



\CH0H— CHOH 



Besides being found in muscle, inosite is of common occur- 

 rence in plants, in the leaves, especially when young, of Vitis, 

 Juglans, etc. ; in the roots and rhizomes of very many plants ; 

 in various seeds and fruits, e.g. Phaseolus, Pisum, and other 

 leguminous seeds, Vitis, various cereals, and oily seeds, such 

 as mustard. 



It may be looked upon as a plastic substance since Maquenne 

 has found that it disappears from the young fruits of Phaseolus 

 as ripening proceeds. 



Preparation. 



The method of separation of inosite from the plant juices is 

 based on the fact that it forms a compound with lead oxide. 



The sap is expressed from the organ, or, if this be imprac- 

 ticable, the parts are ground up very thoroughly with water. 

 The liquid is then filtered and, if it gives an acid reaction, is 

 neutralized by the addition of baryta water. 



A solution of basic lead acetate is then added until no more 

 precipitate comes down. The precipitate consists of a com- 

 pound of inosite with lead oxide (2CgHi.,0^ 5PbO), and is 

 filtered off, then washed and suspended in water, and saturated 

 with a current of sulphuretted hydrogen. The lead sulphide 

 25* 



