8o 



AMERICAN JOURNAL OF BOTANY 



[Vol. 8 



the total number of bundles at the base of the hypocotyl, it therefore 

 becomes a question as to whether we should count each primary double 

 bundle as a single strand or as a double strand; adding, of course, the 

 number of intercalary bundles in each case. 



The distribution of total bundle number at this level according to the 

 former method (primary double bundles counted as one, plus intercalaries) 

 is shown in table 7, for both dimerous and trimerous seedlings. The 

 results are shown clearly in figure 15. 9 The modal number is on 4 (lines 

 75&amp;gt; 98, 139, and 143) or 5 (line 93) bundles in the case of the dimerous 

 seedlings, but invariably on 6 in the trimerous plantlets of the five lines. 

 The distribution of number of bundles is almost wholly skew in the case 

 of the normal seedlings, line 93 being slightly different from the others, but 

 fairly symmetrical in the trimerous series. 



The constants given in table 8 show that on the average the trimerous 

 plants have from 0.77 to 1.91 bundles more than the dimerous plants. 

 This is an excess of from 14.4 to 46.7 percent instead of the 50 percent which 

 one might expect if the increase in number of bundles were proportional 

 to the number of cotyledons or primordial leaves. 



TABLE 8. Statistical constants for total number of bundles at base of hypocotyl of trimerous 

 plants and their normal controls. Primary double bundles are counted as one bundle only 



1 Lines 139 and 143 are in essential agreement with 75, 93, and 98, and 



are not drawn. 



