The Origin of CJirysanthcmuni Scgciwu Plciiimi. 191 



from tlie figures ol)tained in this way. But there is, as 

 we liave already seen, another method of estimating the 

 indivi(hial vahie of a plant, namely that based on a de- 

 termination of the mean character of as many fiowers 

 as possible on a single individual. This raises two points 

 for consideration : first the mode of branching of the 

 corn marigold, and secondly the influence of the devia- 

 tion of the individual from the mean of its race. 



The mode of branching in Chrwsaiitlicinuni scgcfum 

 is as follows. The main stem which arises from the 

 plumule bears two groups of branches; strong ones at its 

 base from the axils of the radical leaves; and, higher up, 

 weaker ones whose vigor first gradually increases and 

 then decreases, as they succeed one another from below 

 upwards. This applies both to their length and to the 

 number and strength of their secondary branches. These 

 secondary branches are, therefore, of the third order; 

 they often bear branchlets of the fourth and even of 

 the fifth order. The flowers that bloom in July, with us, 

 are mostly of the second order, those blooming in August 

 and September of the third and fourth. 



In the course of the summer, and with the flowers 

 on tlie successively higher orders of branches variabilitv 

 is seen to manifest a general decrease. The sides of the 

 curve are, so to speak, drawn in ; the curve itself be- 

 comes narrower. The amount of deviation of the various 

 individuals from the mean of the race decreases, and 

 the mean consequently comes to stand out more boldlv. 

 This is of especial importance in cases in which a curve 

 has been shifted laterally by stringent selection (such 

 as Fig. 32, p. 181) where it might remain doubtful what 

 the shape of the curves would have been if selection had 



