Mutations 



89 



florets scattered over the disk. An indication of the 

 mutation was now seen. 



The next year, 1900, the highest number of rays arose 

 to one hundred, and reached two hundred in 1901. These 



21 22 23 24 25 26 27 28 



B 



FIG. 29. A, Chrysanthemum segetum; B, Chrysanthemum segetum 

 grandiflorum (after purification). Curves of the races after isolation : 

 A, curve of the 13-rayed race in 1894 ; B, curve of the 21 -rayed race 

 in 1897. The ordinates give the number of individuals with like num- 

 ber of ray-florets in the primary inflorescences of the individual plants. 

 The number of ray-florets themselves is given below the abscissa. 



heads were completely double and the mutation had ap- 

 peared, not quite as suddenly, perhaps, as with toad- 

 flax, but nevertheless as surely. The new race was per- 

 manent and constant. 



Complete doubleness caused sterility, so that the race 

 had to be perpetuated from slightly inferior stock. 



Here, again, was the origin of a new mutation produced 

 in control cultures by careful laboratory methods. 



