b., 1921] HARRIS AND OTHERS SEEDLINGS OF PHASEOLUS 



8l 



The variability, both absolute and relative, of the number of bundles is 

 gher in dimerous than in trimerous plants. It is conspicuously higher 

 lines 75, 93, and 98. Thus the standard deviations for the trimerous 

 ilants range from 0.37 to 0.60 in the three lines as compared with 0.91 to 

 .09 in the dimerous controls. The relative differences show that the 

 -ariability of the trimerous plants is from 45 to 60 percent less than that of 

 he dimerous plants. In the case of line 143, however, the difference 

 between the standard deviation of the two types of seedlings is very small- 

 ess, indeed, than the probable error of the difference. Practically the 

 ,ame condition is found in line 139. 



The coefficients of variation show that the trimerous plants have a 

 /ariability in bundle number which is from 5.1 to 10.1 percent of the mean 

 lumber of bundles, whereas the dimerous controls have a variability which 

 s from 8.2 to 22.4 percent of the average number. In lines 75, 93, and 98 

 the difference between the two types is much more conspicuous than in lines 

 139 and 143. 



Since in practically all cases, however, the primary double bundles 

 have already clearly become two strands at the point where the intercalaries 

 appear, it probably gives us a better conception of total bundle number here 

 to count each primary bundle as two, and to add thereto the number of 

 intercalaries. The actual and the percentage distribution according to this 

 method are shown in table 9. Lines 75, 93, and 139 are represented in 



TABLE 9. Total number of bundles at base of hypocotyl in trimerous and dimerous seedlings. 

 Primary double bundles are counted as two 



