51 



woulil iiiecni, ^1 Course, tuat the environment exerted "-' K>&;:ie i.xi- 

 fliience upon the process of le af-siirfaoe increase fas measured 

 by leaf-product), and either of these two criteria would "be a 

 measure ■'-^' ^'-'^ ^ther. But ■^■" coincidence of the two graphs is 

 not by any means -erfect and it becomes necessary to study their 

 differences, especially with reference to the correspondinn- re- 

 lative ^'■alues ""f -^-''^eir ordinates. 



Inspection of the graphs shows that, leaving those fc r 

 Oakland out of account the index of height increase is frequently 

 greater than the other plant jnl"-- -^ \- '-•:- early and late por- 

 tions of the frostless season, and that this relation generally 

 is reversed 'or the middle -ortion. In other terms, the graph 

 for stem elongation generally lies belcv; the other graph for 

 the middle of the season and above it for the beginning and end 

 of the season. In still other words, the seasonal maxima of 

 leaf-product values are generally rela'^'^''^" y higher than those of 

 stem elongation, v/hile the seasonal minima of the former are 

 lower than those of the latter. It r;ay be stated, as an approxi- 

 mation, , that vchen these f^-ro •■l?n+- values are both above 100 

 the leaf-product values are the higher of the tvro, while when 

 both are below 100 the elongation values are the higher. In 

 ^ho r.c,c--. .-.-^ Oakland, "^^--f^^ '^-Tilues ■''■-" -^ omparative? "' -"^-^ low 

 throughoirt the season and y;hile the index of stem elongation 

 reaches Bomewhat above 100 for two periods, this index is 

 never surpassed in magnitude by the ' ^lo-'- ■■ ' _ "_--,,-,-.•: i-,-.-^ 

 crease. 



The generalization Just indicated, being a relation be- 

 tween 'he rates of two -plant processes, seems ^c " --- a Physiologi- 

 cal one, dependent upon the nature of the soy-bean plant, and 



