THE FOOD AND DIGESTION 



By the polymerisation of two monosaccharid molecules 

 with the loss of water, disaccharids, or double sugars, are 

 formed. Thus, two glucose molecules polymerise to form 

 one maltose molecule. 



12 6 = 2 ( c 6 H 12 6 )-H 2 



Maltose is the sugar formed by the action of malt and other 

 vegetable and animal zymins upon starch. By the action of 

 dilute acids and other agents it can be split into two dextrose 

 molecules. Like the monosaccharids, it ferments with yeast. 



Lactose, the sugar of milk, is a disaccharid composed of 

 a molecule of dextrose united to a molecule of galactose 

 with dehydration. It readily splits into these two mono- 

 saccharids, but does not ferment with yeast. 



Dextrose, polymerising with laevulose, yields cane sugar, 

 and this sugar, so largely used as an article of food, can be 

 split into dextrose and lasvulose. It does not reduce Fehling's 

 solution, and does not ferment with yeast. 



By further polymerisation of monosaccharids with the loss 

 of water, molecules of greater size are produced and form the 

 set of substances known as the polysaccharids. Among the 

 simplest of these is dextrin, produced by the polymerisation 

 of twelve molecules of glucose with the loss of twelve 

 molecules of water. 



12(C 6 H 12 6 -H 2 0) 

 = 12(C 6 H 10 5 ) 



Closely allied to dextrin is inulin. But while dextrin is 

 formed of dextrose molecules, inulin contains Isevulose mole- 

 cules. Both are formed from the splitting of the more 

 complex starches. The molecule of soluble starch is built up 

 of no less than thirty dehydrated monosaccharid molecules, 

 and has a molecular weight of 9000. Ordinary starch seems 

 to have a molecular weight of 20,000 or 30,000, .and hence 

 must be of still greater complexity. 



These polysaccharids are distinguished from the sugars by 

 being precipitated from their solutions by the addition of 

 alcohol. They are not oxidised when boiled with caustic 

 potash, nor do they change to alcohol and carbon dioxide 

 under the influence of yeast. In cold neutral or acid solu- 



