352 AMERICAN JOURNAL OF BOTANY [Vol. 8, 



As explained above (p. 346), the slopes for the trimerous seedlings are 

 very greatly influenced by certain aberrant individuals. When these are 

 removed we obtain the equations represented by the broken lines in the 

 figures. 5 The results for the relationship between the number of inter 

 calary bundles and the number of bundles in the epicotyl indicate a positive 

 correlation in all 3 cases when the one extreme plant is removed. 



(3) The coefficients of correlation between total bundles (double bundles 

 plus intercalary bundles) at the base of the hypocotyl and the number of 

 bundles in the central region of the epicotyl, r^ e , are shown in the third 

 section of table 3, and are represented graphically in terms of regression 

 in the upper figures of each panel of diagram 5 for trimerous seedlings and 

 of diagram 6 for normal seedlings. The very gentle slope and the differ 

 ences in direction of the lines for the epicotyl of the trimerous plants, to 

 gether with the irregularity of the empirical means, serve to emphasize 

 the slightness of the relationship between total bundles at the base of the 

 hypocotyl and the number of bundles in the central region of the epicotyl. 

 In the normal plantlets the means are less irregularly distributed about 

 the theoretical lines, but the slope of the lines is very slight, and in one case 

 the regression slope has the negative sign. 



Turning to the correlation constants for more direct numerical com 

 parison, we note that three of the ten constants are negative. The general 

 average is +.0456 for the trimerous and +.1228 for the dimerous seedlings. 



Looking back over diagrams 1-6, one cannot but be impressed by the 

 difference in the slope of the lines showing the changes in number of bundles 

 in the hypocotyl and in the epicotyl respectively associated with variations 

 in the number of bundles at the base of the hypocotyl. The lines for the 

 hypocotyl, without exception, indicate an increase in the number of bundles 

 in the central region of the hypocotyl with an increase in the number of 

 bundles at the base of the hypocotyl. The lines for the epicotyl occasionally 

 show a decrease. Furthermore, the slopes of the lines for the hypocotyl 

 are in general conspicuously steeper thus indicating closer dependence 

 upon the number of basal bundles than those for the epicotyl. 



Turning to table 4 for a numerical comparison of the correlations be 

 tween the systems of bundles on the same side and on different sides of the 

 cotyledonary node, we note that without exception the coefficients of corre 

 lation measuring the interrelationship between the number of vascular 

 elements at the base of the hypocotyl and in the central region of the epi 

 cotyl are markedly lower than those measuring the correlation between the 

 number of vascular elements in the base of the hypocotyl and in the central 

 region of the hypocotyl. 



(B) We now have to consider the problem of the correlation between 

 the numbers of bundles in the central regions of the hypocotyl and of the 



5 When the extreme cases are omitted the equations are: Line 75, = 15.378 + o. 591 /; 

 Line 93, E = 15.670 + 0.096 7; Line 98, E = 14.840 + 0.394 7. 



