14 MANURES FOR FRUIT TREES 



production of essences and oils ; while others, 

 insoluble in the hydrocarbons, tend on splitting up, 

 to produce carbohydrates, tannins and extracts. 



Reverting again to the function of leaves, it 

 may be stated, en passant, that although assimila- 

 tion only goes on during the day-time, root 

 absorption is independent of light. 



According to the tMorie de Ba'eyer, the 

 chemistry evolved in these two functions are 

 represented by the following equations : — 



(^) 6CH,0 = CeH^oO, + H,0 1 ^««^^^^t^«^- 



In the first equation, the carbon dioxide in the 

 presence of moisture is transformed into 

 formaldehyde, and oxygen is returned to the air. 

 In the second equation, formaldehyde becomes 

 polymerised into starch, and water is eliminated. 

 The two actions constitute the function of 

 assimilation. 



As starch is insoluble in cell-sap, it is trans- 

 formed in the presence of moisture, by enzjone 

 action, into glucose or a soluble carbohydrate : — 



(7) CeHioO^-t-H^O^CeHiA, 



and this is utilised by the growing and developing 

 tree or plant ; any reserve material, required for 



