102 THE APPLE 



absence these processes stop. Its absence also results in an ac- 

 cumulation of fats and albumin. Its presence has been shown to 

 be necessary for the formation of lecithin and chlorophyll. Lecithin 

 is a semisoluble substance regularly accompanying fatty matter, 

 but physiologically superior to it because of its partial solubility ; 

 it probably aids in respiration, being the form into which fat 

 must be changed to become combustible in the protoplasm. 



V\c. 44. Commercial fertilizer used 



These trees received nitrogen and phosphate and produced 721 bushels per acre in 1909. 



They are identical with the trees in Fig. 45, except for fertilization. (After Pennsylvania 



State College) 



As might be expected, there is a large demand for phosphorus 

 in the new growth, and consequently an enormous migration from 

 the older portions to the younger. As with most other minerals, 

 during maturity and the later stages of plant growth there may be 

 a considerable loss of assimilated phosphoric acid, as a result of 

 rains and dew. 



In experiments made in England phosphoric acid was found to 

 promote root development very markedly, but not exactly in pro- 

 portion to its supply, as there is an unknown factor affecting re- 

 sults. It is very effective in promoting tillering and, consequently, 

 bud formation in stem and roots. 



