60 ALIMENTATION. 



What has been said regarding sugar as an alimentary 

 principle will apply to starch. Though an abundant and 

 important article of diet, it has been demonstrated by Ham- 

 mond ' and others to be insufficient of itself for the pur- 

 poses of nutrition. 



Vegetable Principles resembling Starch. In certain ve- 

 getables, substances isomeric with starch, but presenting 

 slight differences as regards general properties and reactions, 

 have been described, but they possess no very great interest 

 as alimentary principles, and demand only a passing men- 

 tion. These are, inuline, lichenine, cellulose, pectose, man- 

 nite, mucilages, and gums. 



Inuline is found in certain roots. It is capable of being 

 converted into sugar, but does not pass through the inter- 

 mediate stage of dextrine. It differs from starch in being 

 very soluble in hot water, and in striking a yellow instead 

 of a blue color with iodine. 



Lichenine is found in many kinds of edible mosses and 

 lichens. It differs from starch only in its solubility. 



Cellulose is a substance, generally regarded as identical 

 in all plants, which forms the basis of the walls of the vege- 

 table cells. It exists in greater or less abundance in all 

 vegetables. It is less easily acted upon by acids than starch, 

 but is capable, when treated with concentrated sulphuric 

 acid, of being converted into starch, then into dextrine, and 

 finally into sugar. It is only in soft and recent vegetable 

 products that it can be regarded as an alimentary principle. 



Pectose is a principle which exists, mingled with cellu- 

 lose, in unripe fruits, carrots, turnips, and some other vege- 

 tables of this class. Its composition has not been determined. 

 In ripe fruits it is found transformed into a soluble substance 

 called pecline. This transformation may be effected artifi- 

 cially by the action of acids and heat. Pectine may be pre- 



1 Op. tit. 



