CONDITIONS FOR THE GROWTH OF PLANTS. 21 



on the earth, the following conditions are neces- 

 sary : 



1. The germ or seed from which the plant 

 grows. 



The germ or seed in all cases comes directly 

 from a plant similar to that which is produced 

 when the seed sprouts or germinates, and attains 

 its full growth. 



2. The cradle where the plant is born. 



The plant's cradle is the soil. In the soil the 

 plant spreads its roots, and from it obtains, in 

 great part, the materials necessary for nourish- 

 ment and growth. 



Cases exist where the plant finds its cradle in 

 the air or in the water. These need not, however, 

 be considered in this connection. 



3. The sunshine and the heatshine, which awaken 

 the sleeping germ and call it into activity ; or, in 

 other words, the light and heat which are so 

 essential to a plant's growth. 



4. The nourishment, or the food which the 

 plant takes into its structure and assimilates, and 

 thus causes it to become a part of itself. 



The processes by which a plant causes different 

 materials taken from the soil in which it grows, 

 or from the air around it, to become a part of 



