THE CAEBOHYDKATES. 



^ although "tiiey "cannot be made directly from carbon and 

 water. Most of them contain in a molecule six atoms of 

 carbon or some multiple of six. Many organic compounds 

 of carbon, hydrogen, and oxygen, however, have the two 

 latter in the proportion to form water, but do not belong to 

 the carbohydrates. 



Carbohydrates are found in both the animal and vege- 

 table kingdoms, but are most abundant in the latter. 



The different members of the group differ greatly in 

 their properties, such as the power of crystallization, fer- 

 mentation, reducing effect, action on polarized light, taste, 

 etc. 



They may be divided according to their molecular 

 composition into three classes: 



I. Glucoses, or monosaccharids, C 6 H 12 6 , including: 



1. Glucose, or grape-sugar; also called dextrose. 



2. Fructose, or fruit-sugar; also called laevulose. 



3. Less important are galactose, mannose, and sev- 



eral others. 



II. Saccharoses, or disaccharids, C 12 H 22 11 , includ- 



ing: 



1. Sucrose, or cane-sugar. 



2. Lactose, or milk-sugar. 



3. Maltose, or malt-sugar, and some others. 



III. Amyloses, or polysaccharids, (C 6 H 10 5 ) X , includ- 

 ing: 



1. Starch. 



2. Dextrin. 



3. Glycogen. 



4. Cellulose; also a number of gums and others of 



less importance. 



