622 Mutations 



culture, more than a century ago, as isolated 

 monstrous individuals. They come true from 

 seed, but show deviations from time to time 

 which seem to be intimately linked with their 

 abnormal characters. Apetalous flowers may 

 be considered as another form of monstrosity, 

 and in Salpiglossis sinuata such a variety with- 

 out a corolla made its appearance in the year 

 1892 in the nursery of Vilmorin. It appeared 

 suddenly, yielded a good crop of seed and 

 was constant from the outset, without any sign 

 of vicinism or impurity. 



In several cases the origin of a variet}^ is ob- 

 scure, while the subsequent historical evidence 

 is such as to make an original sudden appear- 

 ance quite probable. Although these instances 

 offer but indirect evidence, and will sooner or 

 later lose their importance, it seems desirable 

 to lay some stress on them here, because most of 

 these cases are very obvious and more striking 

 than purely historical facts. Sterile varieties 

 belong to this heading. Sometimes they bear 

 fruit without kernels, sometimes flowers with- 

 out sexual organs, or even no flowers at all. In- 

 stances have been given in the lecture on 

 retrograde varieties; they are ordinarily as- 

 sumed to have originated by a leap, because it is 

 not quite clear how a loss of the capacity for the 

 formation of seeds could have been si owl v accu- 



