July, 1921] 



THE SEEDLING OF PHASEOLUS VULGARIS 



357 



FABLE 6. Comparison of correlations for trimerous and dimerous seedlings. Differences 

 only (trimerous less dimerous) are given. See tables i and 3 for constants 



tween the numbers of vascular elements on different sides of the cotyledon- 

 ary node as shown in the central and lower section. The exceptions occur, 

 in short, among the relationships which in both types of seedlings are 

 practically zero in intensity. 



We have no explanation to offer of this greater intensity of correlation 

 in the sub-cotyledonary region of the normal seedling. The result is stated 

 as one of the matters of fact demonstrated by the investigation. 



Correlation between Bundle Number in Siblings 



The question will naturally arise as to whether the variability in number 

 of bundles in both hypocotyl and epicotyl and the correlation between 

 bundle number in these two internodes may be due to a differentiation of 

 the parent plants from which the seeds were obtained, either in their genetic 

 composition or because of environmental influences. This problem pre 

 sents many difficulties. Some light may be thrown upon it in the following 

 manner. 



An abnormal and a normal seedling were taken from the same parent 

 plant. Thus it is possible to determine in our series the correlation between 

 the number of bundles in the hypocotyl of an abnormal plant and in the 

 hypocotyl of a normal plant derived from the same parent. If a differentia 

 tion of the parent plants due to either genetic or physiological factors is 

 the underlying proximate cause of the variability and correlation in bundle 

 number in seedlings which we have studied, there should be a correlation 

 between the number of bundles in the seedlings derived from the same 

 plant. 



The correlations between the numbers of bundles in the hypocotyls 



