282 Non-Isolahlc Races. 



wliole set of facts. The variegated sorts are nearly all 

 more or less constant; sometimes to a very small and 

 sometimes to a very large extent. This character has 

 been subjected to what we may call an automatic selec- 

 tion, for every gardener naturally plants out only varie- 

 gated specimens neglecting the green ones ; also it is 

 customary to cut away the green twigs which arise by 

 bud-variation. Here we have a sort of unconscious se- 

 lection which has however been exercised in the same 

 direction for many years, and in many cases through 

 some centuries. 



And what has been effected by this continued selec- 

 tion? Absolutely nothing. At least, so far as we know, 

 nothing more than maintaining the variegated varieties 

 and keeping them in a fairly pure condition. But nothing 

 like fixation has resulted ; that is to say, the varieties 

 continue to produce atavists when grown from seed, and 

 moreover, the pure and constant varieties which corre- 

 spond to them have not been obtained. For in this case 

 these varieties, as we stated above, would have to be the 

 pure yellow ones, such as are known to gardeners under 

 the name of mire a forms. 



All in all there are in our gardens, perhaps twenty 

 or thirty, or even a few more of these aurea forms ; and 

 this number is as nothing compared with the almost un- 

 limited series of variegated forms. Moreover exactly 

 those variegated forms which have been cultivated most 

 carefully and for the longest time have not given rise to 

 aiirea varieties.-^ 



From this discussion I draw the conclusion that con- 

 tinued selection with variegated plants will not of itself 

 lead to the production of constant forms. For this, 



^ See the list on page 270. 



