77 



answered by the behavior of the soy-beans 7.hen ^rown under 

 glass und in a forest. This behavior indicates that evano- 

 ration has only a slight effect on stem elongation as com- 

 pared to sunshine intensity. The consideration of the covered 

 and forest station which will appear later, will justify this 

 statement . 



Relation between dry ?:eip-ht and the three climatic con - 

 diti ons . '^he last part of the discussion of the four-week 



data will attempt to sho^r that the dry weight of the plants 

 and the climatic conditions may be correlated using the assump- 

 tions nade in correlating two-week leaf -product and climate. 

 As was no'ed in the treatment of the two-week d tta, these as- 

 sumptions may be expressed in the following way: 



fTL) X fJ^Tj 



^ ~ ""tlij 



in which the symbols have the same meaning as in the discussion 

 of the two-week data. It was previously brought out that the 

 above equation states the rate of growth to be directly pro- 

 portional to some function of the light, directly proportional 

 to some function of the temperature, an' inversely proportional 

 to some function of the evaporation, f (L) , f[T), and -ffEj are 

 used in the equation instead of L, T, and E since the environ- 

 mental conditions do not affect the plant in a simple direct 

 way, but bear a complicated tmknown relation to the growth 

 rate. The physiological index, used as a means of expre ";sing 

 temperature in "rhis study Is an attefipt to evaluate f(_T) directly- 

 Ai has b en suggested by Livin -ston, corresponding indices 



