CHAPTER XII 

 DANIEL'S EXPERIMENTS AND CONCLUSIONS 



207. Functional capacity of plants. — Daniel gives the 

 following broad generalizations on the relationship be- 

 tween absorption, assimilation and transpiration in 

 plants. By functional capacity is meant the processes 

 involved in the absorption and utilization of crude ma- 

 terials by the plant. If the function of absorption or the 

 total absorption from external surroundings be repre- 

 sented by CA, and the functional capacity of consump- 

 tion or total consumption at the points where the sap is 

 used up be represented by CV, then in a plant in com- 

 plete equilibrium as regards its general nutrition CV= 

 CA and ^ =1, If, however, aerial consumption is 

 greater than the usual subterranean absorption, then the 

 formula ~> 1. This corresponds to growth in dry or 

 poor soil. When absorption is greater than consumption, 

 as in moist or rich soils, the formula becomes —§^< 



Conditions similar to these are sometimes brought 

 about by grafting. The cicatrization of the grafted 

 plants and the intercalcated tissue between stock and 

 cion interfere with the condition of sap, modifving it 

 both in quantity and quality. These modifications of 

 the cion are equivalent to growth in a drier, poorer 

 medium than the normal. In grafting it is also necessary 

 to keep in mind the relative functional capacities of the 

 two grafted plants. For example, if the functional ca- 

 pacity of consumption is greater in the cion than in the 

 stock this condition becomes exaggerated by the scar 

 of cicatrization when the two plants are grafted, and the 

 graft either fails to take or makes a poor growth, cor- 

 responding to that in poor dry soil. The chance for mak- 



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