86 The Feeding of Animals 



heat, ferments and hot acids, certain carbohydrates may 

 be changed to other bodies of the same class. This 

 fact is important in the arts, and no less so in plant 

 and animal nutrition. The movements of these com- 

 pounds in plants and their uses as nutrients depend 

 largely upon these transformations, as do also certain 

 phenomena in cooker^^ 



Heat is one immediate cause of some of these 

 changes. Starch, when heated, becomes dextrine, a 

 water-soluble, gum -like substance. This occurs in 

 baking corn and wheat bread; so it does in toasting 

 bread, and the bread -crust tea of the sickroom is in 

 part a solution of dextrine. Probably this substance 

 is digested with greater ease than starch, because it is 

 an intermediate stage between starch and glucose, the 

 latter being the final product. 



Hot, dilute acids, even the vegetable acids, such as 

 those found in vinegar and in fruits, transform starch, 

 dextrin, gums and pectin bodies into various sugars, of 

 which dextrose is the principal one. Saccharose is 

 changed to dextrose and levulose in the same way. 

 These chemical facts find an application in the manu- 

 facture of glucose from cheaper materials, and in cook- 

 er}' where vinegar and acid fruits are used. 



These transformations are also brought about by 

 the influence of bodies called ferments. For instance, 

 the carbohydrates in a grain of barley are largely not 

 available for nourishing the new growth that takes 

 place during germination, because, being mostly insolu- 

 ble, they cannot be transferred from the seed to the 

 point where new tissue is formed. It is so arranged 



