58 THE PUlNCirLES Of AGUlCL'LTUUE. 



1. TJie Absorption of Molst^ire. — It is evident that 

 the nutritive substances contained in the seed cannot 

 pass into the phint and support growth while in a dry 

 state. The seed must be saturated with moisture, so that 

 there may be a medium through wliich these substances 

 may pass to the point in the growing plant where they 

 are needed. 



2. A Change in the Nutritive Substances. — The sup- 

 plies of food stored in the seed arc not generally in a 

 suitable form to support the plant, but must first be 

 changed. They are dissolved in the moisture, and con- 

 verted by chemical processes into the proper foi-ms. An 

 instance of this is the conversion oi starch into sugar. 

 The formula for starch is C.JTioOj, and for the glucose 

 sugar obtained from it, C.jlTioO,;. I'he latter is obtained 

 from the former by the addition of oxygen and hydrogen. 



In the process of malting barley and other kinds of 

 grain, the aim is to obtain these same chemical changes. 

 The grain is soaked and allowed to si)rout until the 

 starch and other sul)stances are converted into sugar, 

 dextrine, etc. The process is then stopped by drying, 

 and the new substances arc extracted from the grain to 

 form malt. 



3. The Production of Heat. — The changes above re- 

 ferred to are largely due to oxidation, or the coml)ina- 

 tion of oxygen with the substances of the seed. Tliis, 

 as in other instances of oxidation, ])roduces heat. 



If a large num1)cr of seeds are lieaped togcither, as in 

 manufacturing malt, the mass becomes very warm, — so 

 much so that care is re(|uir('(l to pi-eNcnt the gi-ain from 

 spoiling. This heat, deveIo])(Ml in tlie s]iroutiiig seed, is 

 of some service at times when the temperature outside 

 is too low. 



