Production of Double Flowers 505 



that this visible leap directly corresponded to 

 that inner change, which brought about the com- 

 plete inheritability of the new peculiarity. It 

 is very interesting to observe how completely 

 my experience agrees with the results of the 

 observations of breeders at large. No doubt 

 a comparison is difficult, and the circumstances 

 are not adequate to a close study. 



Isolation and selection have been applied com- 

 monly only so far as was consistent with the re- 

 quirements of practical horticulture, and of 

 course a determination of the hereditary per- 

 centage was never made. The disregard of this 

 feature made necessary a greater length of time 

 and a larger number of generations to bring 

 about the desired changes. Notwithstanding 

 this, however, it has been seen that double va- 

 rieties are produced suddenly. This may have 

 occurred unexpectedly or after a few years ' ef- 

 fort toward the end desired. Whether this 

 sudden appearance is the consequence of a 

 single internal differentiating step, or of the 

 rapid succession of lesser changes, cannot yet 

 be made out. The extreme variability of dou- 

 ble flowers and the chance of their appearance 

 with only slight indications of the previous pet- 

 aloid alterations of a few stamens may often re- 

 sult in their origin being overlooked, while 

 subsequent generations may come in for full no- 



