366 HOW CROPS GROW. 



During the latter stages of germination it gathers its 

 nutriment both from the parent seed and from the exter- 

 nal sources which afterward serve exclusively for its 

 support. 



Being fully provided with the apparatus of nutrition, 

 its development suffers no check from the exhaustion of 

 the mother seed, unless it has germinated in a sterile 

 soil, or under other conditions adverse to vegetative life. 



CHAPTER II. 

 1. 



THE FOOD OF THE PLANT WHEN" INDEPENDENT OF THE 



SEED. 



This subject will be sketched in this place in but the 

 briefest outlines. To present it fully would necessitate 

 entering into a detailed consideration of the Atmosphere 

 and of the Soil, whose relations to the Plant, those of the 

 soil especially, are very numerous and complicated. A 

 separate volume is therefore required for the adequate 

 treatment of these topics. 



The Roots of a plant, which are in intimate contact 

 with the soil, absorb thence the water that fills the active 

 cells ; they also imbibe such salts as the water of the soil 

 holds in solution ; they likewise act directly on the soil, 

 and dissolve substances, which are thus first made of 

 avail to them. The compounds that the plant must 

 derive from the soil are those which are found in its ash, 

 since these are not volatile, and cannot, therefore, exist 

 in the atmosphere. The root, however, commonly takes 



