342 CHEMISTRY. 



tioned is the production of a substance which so acts upon 

 these materials as to make them soluble. This substance 

 is formed by the union of the oxygen of the air with some 

 of the gluten, and is therefore oxidized gluten. This union 

 will not take place unless there be moisture, just as iron 

 will not rust or oxidize in perfectly dry air. The substance 

 thus produced is called diastase. It has the power of con- 

 verting the starch into dextrin, and also into sugar, and 

 both of these substances are soluble. It also in some way 

 renders the gluten soluble. But little diastase is required 

 to produce these changes, and therefore but little of the 

 gluten is converted into diastase. There are some very 

 familiar examples of these changes. The malt of the 

 brewer is sweet and mucilaginous to the taste, because in 

 the germination of the barley the diastase converted some 

 of the starch into sugar and dextrin, the latter giving the 

 malt its mucilaginous character. For the same reason 

 when potatoes sprout they become soft, mucilaginous, and 

 sweet. 



473. Root and Germ. From the materials contained in 

 the seed, thus rendered soluble, the root is formed down- 

 ward and the germ upward. These are solid formations. 

 Observe how they are made. It is not by chemical power, 

 as particles are arranged in various crystalline forms. The 

 branching germ and root are not formed as the lead-tree 

 is, noticed in 373. In this latter case particles are de- 

 posited on each crystal in regular layers, each layer outside 

 of that deposited before it. But in the formation of the 

 germ and root life is ever pushing along, making chan- 

 nels for the materials of the seed to flow in. By the time 

 that these materials are used up in the formation of the 

 plant it becomes fitted to go on in its growth by absorb- 

 ing materials from the earth and from the air, for the 

 same living power which constructs the channels for it 



