110 



VARIATION AND DIFFERENTIATION IN CERATOPHYLLUM. 



We note at once from this table that the most frequently occurring 

 whorls at the nodes where branches originate are those having 10 leaves 

 (with the single exception of Series V, in which the 9 and 10 leaved 

 whorls are approximately equally frequent) . Further, it appears that 

 generally whorls having a small number of leaves do not occur at the 

 origin of branches, though there are individual exceptions. 



The constants for the largest of these distributions are given in 

 table 55. 



Table 55. —Constants for variation in leaf-number in whorls at which branches 



originate. 

 [Unit = 1 leaf.] 



From this table the following points are to be noted: 

 (a) The mean number of leaves in the whorls where branches start 

 is relatively high. If we compare the values given in this table with 

 those for the different axial divisions of the plant presented earlier in 

 the paper (tables 6, 13, 15, 18, 23, and 24) we see that these whorls 

 agree more closely in type with those borne on the main stem than with 

 any others. 



