Mutations 



87 



form has on the average twenty-one petals on each flower. 

 In the population of the next generation there appeared 

 one plant having twenty-one petals, but on one of its 

 secondary heads twenty-two petals were found. This 

 had never been observed before. This plant was the 



FIG. 27. Chrysanthemum inodorum plenissimum : A, inflorescence with 

 central disk of tube florets (fertile) ; B, with scattered tongue florets 

 in the disk (half fertile) ; C, highest degree of " doubling " (sterile). 



beginning of what developed later into the desired muta- 

 tion. 



This plant produced the next year (1897) plants having 

 thirty-four rays to the head. Next year (1898) this was 

 increased to forty-eight ; next year (1899) to sixty-six. 



