The Origin of Chrysanthcimun Scgctwn Plcnwn. \77 



explanation suggested by the double curve has thus been 

 fully substantiated by the result of selection. On the 

 other hand it is perfectly plain that the dimorphic curve 

 is not simply the sum of the two monomorphic ones. 

 The mixed assemblage does not simply contain the two 

 mixed races, either in equal parts or in any other pro- 

 portion. It cannot be synthesized from its components. 

 This is proved by two circumstances : on the one hand 

 by those parts of the curve that lie outside the maximum 

 ordinates, on the other by the middle part. The two 

 component curves begin at 7 and end at 28 {2>2) and 

 their sum should do so too. But the curve of the mixed 

 race is limited by 11 and 23. This is seen more clearly 

 by looking at the ordinates 12 and 22, since there are 

 far too few individuals in these in Fig. 30. Thus we 

 see that the limits of the curves are, so to speak, "drawn 

 in" in the mixture. On the contrarv the individuals are 

 heaped up between the two apices. Moreover in this 

 part there is a secondary maximum. This is seen at 17, 

 but in the commercial mixture of 1895 falls on 16-^ ac- 

 cording to the figures given above (see p. 172). 



We come noiv to the double race. It is a well-known 

 saying amongst horticulturists, that any one who wishes 

 to obtain novelties must be eagerly on the lookout for 

 small differences (See Vol. I. Part I, p. 185, and this 

 volume, § 2, p. 9). If these deviations are not cases of 

 fluctuating variability but strike the eye by the fact that 

 they are much rarer than these, it is probable that they 

 are the external manifestations of semi-latent characters. 

 If this is actually the case it is further probable that tlie 

 character can be brought bv isolation and selection to 



^ i6 (= 3 + 5 + 8) is one of the subsidiary numbers in Lud- 

 wic/s law. Tlie question arises whether by the crossing- of two pure 

 races these subsidiary numbers may arise elsewhere also. 



