July, 1921] THE SEEDLING OF PHASEOLUS VULGARIS 343 



The correlations are without exception positive in sign and of a material 

 Drder of magnitude. They have been expressed in terms of regression on 

 iiagram I for trimerous seedlings and on diagram 2 for dimerous seedlings 

 ;&amp;gt;f the five lines. 2 



Primary Double Bundles and Mid-region of Hypocotyl 



The constants showing the relationship between number of primary 

 double bundles and number of bundles in the central region of the hypo- 

 :otyl, r ph , are shown in the first section of table I. They are positive and 

 statistically significant in all cases in both dimerous and trimerous seedlings. 

 The average value of the coefficient for the five lines investigated is +.3810 

 ifor trimerous seedlings and +.5086 for dimerous seedlings. 



Diagram 2 shows that in the case of the normal plants of lines 75, 93, 

 and 143 a straight line represents very well indeed the changes in the mean 

 number of bundles in the hypocotyl with variations in the number of pri 

 mary double bundles at the base of the hypocotyl. In line 98 the agree 

 ment is apparently not so good. This is, however, attributable to the 

 fact that of the 183 plants only two have more than 5 primary bundles. 

 Of these two, one plant is recorded as having 8, which is twice*the normal 

 number. In line 139 only plants with two classes of seedlings, those with 

 4 or 5 primary bundles, are available, and since the regression line must 

 connect the two means it is idle to discuss linearity of regression. 



Turning to the trimerous plants represented in diagram I , we note that 

 because of the small number of plants with other than 5 or 6 primary double 

 bundles the distribution of the empirical means is very irregular indeed. 

 There is some suggestion of non-linearity, but the number of seedlings in 

 the more extreme classes is so small for every line that little stress is to be 

 laid upon them. 



In both normal and abnormal plants the slope of the regression line is 

 rather steep, showing a material change in the number of bundles in the 

 central region of the hypocotyl with variations in the number of primary 

 double bundles at the base of the hypocotyl. 



Intercalary Bundles and Mid-region of Hypocotyl 



The correlation between the number of intercalary bundles and the 

 total number of bundles in the hypocotyl, r^ are shown in the second 



2 The equations on the diagrams show the regression of the number of bundles in 

 the central region of the hypocotyl, H, and in the central region of the epicotyl, E, on the 

 number of primary double bundles, P, at the base of the hypocotyl. The empirical means 

 for the hypocotyl are represented by solid dots, while those of the epicotyl are represented 

 by circles. In both cases the empirical mean number of bundles for the same organ are 

 connected by solid lines when the number of sections averaged was five or more, but by 

 broken lines when the number available was four or less. Fortunately for purposes of 

 graphical representation, the mean number of bundles in both hypocotyl and epicotyl 

 can be drawn on the same diagram. Only the lower lines in each of the five panels of the 

 two diagrams require consideration for the moment. 



