The Origin of Chrysanthemum Scgctnm Plenum. 165 
reasons. In botanical gardens, too, both sorts are often 
grown together; and, frequently, simply under the name 
of C. segetum. 
This mixed assemblage gives rise to a dimorphic 
curve; 1 but the two groups of individuals which com- 
pose it can easily be isolated by selection. Then the 
C. segetum grandiflorum proves to have a mean of 21 
ligulate florets, around which variation practically takes 
place in the same way as in the 13-rayed race (i. e., the 
wild species), except that it has a tendency to multiply 
the number of rays beyond the limits of a normal OUETE- 
LET'S curve ; a fact which indicates discontinuous varia- 
tion. 2 
This slight indication was the starting point for my 
experiment. In 1897 I chose a seed-parent with 34 rays 
for the 1898 crop, and reached 49 rays. 3 Proceeding 
in the same way I reached 67 in 1899 and about 90 in 
1900 in the best inflorescences. Up till 1899 the ligulate 
florets only appeared in the circumference, the disc con- 
sisting solely of tubular florets. In this year, however, 
there appeared 2 or 3 ligulate florets in the midst of the 
disc of a few flowerheads on a single plant. This was 
the first indication of the double race. Therefore I only 
sowed the seeds of this one plant in 1900, and from that 
the race was fully developed (Plate II). Apart of course 
from eliminating the possible effects of crossing, it needed 
no further selection ; a too rigid selection was moreover 
1 Eine zwcigipfelige Variationscurve, Archiv fiir Entwickelungs- 
mechanik der Organismen, Leipsic, 1895, p. 52. 
~ Compare the half curves (p. 26) and the note on p&ge 29. See 
also Ucber halbc Galton-Curven als Zeichen discontinuirlicher Varia- 
tion. Berichte d. deutschen bot. Gesellschaft, Vol. XII, p. 197. 
3 Ucber Curvcnsclcction bei Chrysanthemum scgetuui. Same jour- 
nal, 1899, Vol. XVII, p. 84. 
