FERTILIZERS: 



Their Source, Purchase and Use 



SOMETHING ABOUT PLANTS. 



CIRCULATION. 



1. The higher plants (Fruit and Forest trees) have 

 a well defined circulatory system. Beginning with 

 the absorption by the root , hairs of soil moisture, 

 containing dissolved plant food, one set of tissue 

 termed xylem carries this moisture or sap upward 

 into the leaves and is there lost. In the leaf 

 the sap is transformed or elaborated largely by sun- 

 light, according to the plant's nature and needs, and 

 returned to the branches and trunk of the tree and 

 its fruit, by another distinct set of tissue termed 

 phloem. Both these sets of tissue are, roughly 

 speaking, found in the "Cambium" or sap layer of 

 the bark. They are between the real bark and the 

 wood of the tree. Wood is built up on one side and 

 bark on the other. In a cross section of a limb or 

 trunk of a tree these different tissues might be illus- 

 trated, as in Fig. 1. 



The life of the tree is in the cambium. When we 

 bud or graft it is cambium layer contact we want in 

 both stock and scion. If the cambium is severed 

 completely around the tree it dies. All of the soil 

 derived plant foods enter the tree through its xylem 

 tissue, found in the cambium layer. 



