6 The Significance of Horticultural Varieties. 



sliort and lack precision being much inferior in this re- 

 spect to the accurate accounts that are given of artificial 

 crossings. I shall bring together the most important 

 facts that I have been able to find, in the following sec- 

 tion (§2). 



In order to penetrate more deeply into these phenom- 

 ena I have endeavored to apply this method to a series 

 of cases. W\\\\ the help of control experiments, and by 

 kee])i ng detailed records, I succeeded in finding out how 

 such novelties usually develop themselves. Just as hap- 

 pens in practice, I was successful with some cases but not 

 witli others. And the correspondence between my results 

 and the experience of breeders seems to me to be so com- 

 plete that my experiments may simply be taken as in- 

 stances of the method under discussion. 



I propose to distinguish, therefore, between highly 

 variable and only slightly variable novelties. The lat- 

 ter are generally assumed to be instances of single var- 

 iations which arise suddenly. In the case of these I 

 shall, therefore, only have to discuss their origin and the 

 question of their constancy. (Chapter IV of this Part.) 

 Much more important from the critical standpoint are the 

 ^'arieties with a high degree of fluctuating variability, i. e., 

 those very cases which passed for instances of the origin 

 of new characters by artificial selection (Chapters II and 

 VIII). As examples of this I refer to variegated leaves 

 and to double and striped flowers. 



If we now compare, from a theoretical standpoint, 

 this high variability with the normal examples which we 

 dealt with before (Vol. I, pp. 47-52 etc.) we shall see 

 tliat the two are not exactly the same. In variegated 

 leaves the yellow alternates with the green, in semi-double 

 flowers the petaloid stamens alternate with normal ones 



