112 



VARIATION AND DIFFERENTIATION IN CERATOPHYLLUM. 



plant, it may safely be concluded that the branching exercises a specific 

 influence. 



In order to test this matter it is necessary to know first of all some- 

 thing about the positions at which branches originate. Is the chance 

 of a branch occurring the same for all nodes? Or is branching more 

 abundant in some positions on the axes of the plant than in others? 

 To answer these questions the frequency of occurrence of branches at 

 the different nodes must be determined. This has been done for the 

 secondary branches of the first four series, with the results shown in 

 table 57. The way in which the table was made was to enter for each 

 plant the number of secondary branches which originated at specified 

 nodes on primary branches, the nodes being numbered in order, begin- 

 ning with 1 as the most proximal. In case two secondaries arose at the 

 same node each was entered separately. 



Table 57. — Frequency distributions showing position of secondary branches. 



