4 The Significance of Horticultural Varieties. 



The development of the statistical treatment of varia- 

 tion which took place after Darwin's time, allows of an 

 altogether different conception of the phenomena than 

 was possible some fifty years ago. It was shown that 

 the fluctuation of characters is due to their development 

 to a greater or less degree. But the character in ques- 

 tion does not vary in any other than these two directions. 

 The variation is linear (Vol. I, p. 118). It increases 

 or diminishes but creates nothing new. New characters 

 can arise, so to speak, alongside of it, but they arise 

 independently of the fluctuation of the old ones. 



This applies to the case before us. The variations 

 which the horticulturist looks for and then works up 

 are not variations of the old characters ; such may indeed 

 give rise, by selection, to improved races, but not to 

 new types (Vol. I, p. 82). The required deviations are 

 anomalies, as in the example of the origin of double 

 flowers, just cited. When such an anomaly arises we may 

 be sure that the new character already existed in the 

 internal organization of the plant. Where it springs 

 from and how it arose is a matter of indifference to the 

 breeder : he has got it and can work it up. In other 

 words : "The first condition necessary for raising a nov- 

 elty is to possess it" (Vol. I. p. 185). , 



In this connection two cases are distinguished in prac- 

 tice according as one is dealing with apparently invariable 

 forms, or with forms exhibiting a high degree of fluctu- 

 ating variability. In the former case all that has to be 

 done is to isolate the novelty and to free it of possible 

 impurities introduced by crossing. If this can be done 

 without much difficulty the variety is perfect and con- 

 stant from the beginning and needs only a few vears of 

 multiplication before it can be put on the market (Vol. 



