ROOT GROWTH AND TEMPERATURE 333 



erate at first and thus that the ''maximum" rate was not the 

 rate at first noted. The results of the present study, in which 

 young as well as relatively old roots were used and in which the 

 experiments were continued over a relatively long period, sug- 

 gest that possibly the differences in results obtained by the two 

 writers may lie in the possible differences in the organs studied 

 with respect to the period of most active growth, that is, to the 

 "grand period." Experiments conducted prior to this period 

 would exhibit an increase in the rate of gro^vth with the passage 

 of time up to the attainment of the maximum rate at the crest 

 of the "grand period." And, on the other hand, experiments 

 conducted after the passing of the "grand period," would show 

 a fairly level growth curve, or a descending one. 



