402 JOUKNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



means of its roots derives from the soil, usually in the form of nitrates), 

 earth salts, and water. 



Of all the processes that constitute links in the chain of still life, 

 none are more wonderful than those associated with the making of plant 

 food by the plant itself. 



Fig. 62. 



The chlorophyll granules embedded in protoplasm, causing the green 

 colour of leaves, form the field of chemical activity. Their function is to 

 find the nutriment for the leaves and, through them, the plant during the 

 active periods of existence ; but this function cannot be exercised unless 

 they are receiving the chemically active or actinic (or, shall we say, elec- 

 trically energising) rays of the sun, or its substitute, the arc electric light. 



