H. M. Leakb 235 



the consequence. Again, dwarfing arises through numerous causes and 

 leads to delay in the production of the first flowers. In one case plants 

 of a monopodial type, with a normal vegetative period of over 200 days, 

 commenced flowering within 100 days from the date of sowing and 

 before they had been planted out. All cases where any such abnor- 

 mality is apparent have been omitted from the following records. 



The interrelation between the type of branching and the len,gih of 

 the vegetative period. 



The two characters just dealt with are mutually dependent. A 

 plant of the sympodial type will commence flowering shortly after the 

 secondary branches have developed, while a plant of the monopodial 

 type will not flower until the tertiary branches develope. This lengthen- 

 ing of the vegetative period is shown in Table XV, in which the length 

 of the vegetative period of some of the more important types are 

 recorded. The interdependence becomes still more marked when a 

 continuous series, such as is obtained in the F^ and subsequent genera- 

 tions of a cross, is considered. For this purpose the plants may be 

 associated into groups in which the length of their vegetative periods is 

 similar, each group being formed by the plants which flower during a 

 ten-day interval. This method has been adopted for the series derived 

 from the F^ generation of the crosses between types 3 and 4 and 

 between types 3 and 9, and the results are recorded in Table XVII 

 (cf. author's note). The figure given opposite each ten-day interval 

 indicates the average type of branching occurring in plants falling 

 within that interval and is obtained by adding the numbers indicative 

 of the type of branching of each plant (100, 75, 50 or 0) and dividing 

 by the total number of plants. 



Tables XXII — XXV show the same interrelation in the ^3 series only 

 in a slightly diSerent and more detailed manner, the ten stages latterly 

 recognised in the type of branching as above described, and two- and 

 five-day intervals being respectively substituted for the four stages and 

 the ten-day intervals. The closeness of the interrelation is given by 

 the coefficient of correlation (Davenport (6)). This has been worked 

 out for the series given in Table XXIV and found to be '6819. 



This interrelation, or correlation, is, therefore, a definite fact depen- 

 dent on the limitation of the flower-producing habit to the sympodial 

 branches. What appear to be two characters are merely two outward 

 expressions of the same structural peculiarity. In other words a 



