PRODUCTIVE GARDENING. 93 



its tissues are everywhere bathed in nitrogen gas. 

 To make the nitrogen available for the purpose 

 of nutrition it must be made into soluble com- 

 pounds called nitrates, and must be supplied in 

 dilute watery solution. 



Such nitrates, therefore, are among the most 

 important of the soluble compounds that must 

 be contained in the medium surrounding the 

 roots of the plant. Sucked up by the rootlets in 

 dilute solution, along w T ith much smaller quan- 

 tities of phosphorus and potash and the other 

 essential minerals, it is carried to the plant cells 

 and ultimately compounded with sugars made in 

 the leaf laboratory to make living protoplasm 

 and thus to promote the growth and develop- 

 ment of the plant. 



The Finished Product 



This protoplasm is, of course, in the last analy- 

 sis the vitally important substance. Without it 

 there is no life. Even the chlorophyll body is 

 itself a protoplasmic substance and establishes 

 its workshop in a protoplasmic cell. All the life 

 processes — growing, flowering, fruiting — are 

 linked with the protoplasmic activities, just as 

 are all the life processes of animals of every kind. 



But from the standpoint of the gardener, 

 which furnishes our present outlook, interest may 



