612 Mutations 



of a new horticultural variety has been record- 

 ed, and I must apologize for the necessity of 

 again quoting many variations, which have pre- 

 viously been dealt with from another point of 

 view. In such cases I shall limit myself as 

 closely as possible to historical facts. They have 

 been recorded chiefly by Verlot and Carriere, 

 who wrote in Paris shortly after the middle of 

 the past century, and afterwards by Darwin, 

 Korshinsky, and others. It is from their writ- 

 ings and from horticultural literature at large 

 that the following evidence is brought together. 

 A very well-known instance is that of the 

 dwarf variety of Tagetes signat a, which arose in 

 the nursery of Vilmorin in the year 1860. It 

 was observed for the first time in a single indi- 

 vidual among a lot of the ordinary Tagetes sig- 

 nata. It was found impossible to isolate it, but 

 the seeds were saved separately. The majority 

 of the offspring returned to the parental type, 

 but two plants were true dwarfs. From these 

 the requisite degree of purity for commercial 

 purposes was reached, the vicinists not being 

 more numerous than 10^ of the entire number. 

 The same mutation had been observed a year 

 earlier in the same nursery in a lot of Saponaria 

 calahrica. The seeds of this dwarf repeated the 

 variety in the next generation, but in the third 

 none were observed. Then the variety was 



