VARIATION IN DIFFERENT PORTIONS OF PLANT. 



45 



tinctly more skew in the whorls on primary branches than in those in 

 the main stem; (6) the primary-branch whorls are the more variable; 

 (c) the mean number of leaves per whorl is 0.8988 higher in the main- 

 stem than in the primary-branch whorls, while the modal number of 

 leaves per whorl is only 0.6462 higher; (d) the sign of the kurtosis 

 changes in passing from main-stem to primary branches. 



From the results presented in this section we may conclude that 

 whorls borne on secondary branches are as a class differentiated from 

 those borne on either the main stem or primary branches. The changes 

 in the constants as we pass from primary to secondary branches are 

 similar in kind to those which we find in passing from main-stem to pri- 

 mary-branch whorls. The most important of these changes are (1) the 

 lowering of the mean number of leaves to the whorl, and (2) the increase 

 in the variation in this character. 



VARIATION IN WHORLS ON TERTIARY AND QUATERNARY BRANCHES. 



As the number of whorls is comparatively small in these portions of 

 the plant we may conveniently consider tertiary and quaternary branches 

 together. It will be understood that by "tertiary branches" are meant 

 those which arise from secondary branches, and by "quaternary" those 

 which arise from tertiaries. 



Table 21. — Frequency distributions for variation in leaf-number in whorls on 



tertiary branches. 



The frequency distributions for tertiary and quaternary branches 

 are given in tables 21 and 22, respectively. 



The totals here are so small that much regTilarity in the distribu- 

 tions can not be expected, nor can very accurate comparisons between 



