•2~2 



THE AMEBIC AN NATURALIST [Vol. XLIII 



From this slight indication De Vries selected for three 

 years more and found that the 



average number of rays increased rapidly and with it the maximum 

 of the whole strain. The average came up from 21 to 34. . . . The 

 largest numbers determined in the succeeding generations increased by 

 leaps from 21 to 34 in the first year, and thence to 48 and 66 in the two 

 succeeding summers. 



Up to this time, while there was a great increase in the 

 number of ray florets, there was no trace of doubling, but 

 in a few of the best heads "the new character suddenly 

 made its appearance. ' ' If sudden, the step was certainly 

 a very modest one. A single plant was found in which 

 careful inspection revealed 1 ' three young heads with some 

 few rays in the midst of the disk." "Had the germ of 

 the mutation," asks De Vries, "lain hidden through all 

 this time? Had it been present, though dormant; in the 

 original sample seed ? Or had an entirely new creation 

 taken place during my continuous endeavors? Perhaps 

 as their more or less immediate result?" It is stated 

 that "The new variety came into existence at once"— 

 but when? While certain that a mutation must have 

 appeared, De Vries is uncertain when and where it ap- 

 peared. "The leap," he says, " may have been made by 

 the ancestor of the year 1895, or by the plant of 1899 

 which showed the first central rays, or the sport may have 

 been gradually built up during these four years" (italics 

 mine). 



During the next two years improvement by selection 

 was kept up. 



?ty which is pronounced "permanent and con- 

 as i .reduced whose lower limit of the number 



