56 ALIMENTATION. 



are soluble in water and in alcohol ; they are inflammable, 

 leaving an abundant carbonaceous residue, and giving off a 

 peculiar odor of caramel; and are capable of being con- 

 verted, in contact with ferments and with nitrogenized 

 principles, into alcohol and carbonic acid, and into lactic 

 acid. They are also capable of other modifications when 

 treated with the mineral acids, or with alkalies, which are 

 interesting more in a chemical than a physiological point 

 of view. 1 Of all the varieties of sugar, that made from the 

 sugar-cane is the most soluble, the sweetest, and most agree- 

 able. Beet-root sugar, so extensively used in France, is per- 

 haps as agreeable, but not so sweet. 



Much of the sugar used in the nutrition of the organism 

 is formed in the body from the digestion of starch. This 

 transformation of starch may be effected artificially. The 

 sugar thus formed is called glucose, and is identical in com- 

 position with grape-sugar. Except in the milk during lacta- 

 tion, this is the only form in which sugar exists in the organ- 

 ism, all the sugar taken as food being converted into glucose 

 before it is taken into the blood. 



Starch. A non-nitrogenized principle, closely resembling 

 sugar in its ultimate composition (C 12 H 10 O 10 ), is contained 

 in abundance in a great number of vegetables. It is found 

 particularly in the cereals (wheat, rye, corn, barley, rice, 

 oats), in the potato, chestnuts, and in the grains of legumin- 

 ous plants (beans, peas, lentils, kidney-beans), in the tuber- 

 ous roots of the yam, tapioca, and sweet-potato, in the 

 roots of the Marantd arundinacea* in the sago-plant, in the 

 bulbs of orchis. 3 In the cereals, after desiccation, the pro- 

 portion of starch is, in general terms, between sixty and 



1 The various tests for sugar have been considered in vol. i. (Introduction). 



a The creeping roots from which the substance known as arrow-root is manu- 

 factured. 



3 PATEN, Precis Theorique et Pratique des Substances Alimentaires, Paris, 

 1865, p. 232. 



