88 AMERICAN JOURNAL OF BOTANY [Vol.8 



normal plants of lines 75, 93, and 98. In these, bundle number ranges from 

 8 to 1 8 with a relatively large number of bundles in the lower classes. The 

 modal number of bundles in the hypocotyl of normal seedlings of lines 

 75, 98, 139, and 143 is 8, while in line 93 it is 10. 



The normal plants of the five lines differ conspicuously in variability. 

 The number of seedlings falling in the modal class is relatively small and 

 the range of variation relatively wide in lines 75, 93, and 98 as compared 

 with line 139. Line 143 occupies an intermediate position in this regard. 



In all the lines except 93 the distribution of number of bundles in the 

 hypocotyl of normal seedlings is wholly skew, the frequency decreasing 

 from the modal number (eight) towards the upper end of the range. In line 

 93 (figure 18) the distribution is also skew, but the frequency decreases from 

 the modal number (ten) towards both ends of the range. 



In the trimerous plantlets of all five series the modal number of bundles 

 in the mid-region of the hypocotyl is 12. The extent of concentration into 

 the modal class and the range of variation differs greatly in the five lines. 

 This is very narrow in lines 98 and 139 and relatively wide in line 143. 



The frequency distribution and figures bring out very clearly indeed the 

 differentiation of the trimerous and dimerous seedlings in the number of 

 vascular bundles. 



TABLE 12. Statistical constants for number of bundles in hypocotyl of trimerous and dimerous 



seedlings 



