The Origin of Chrysanthemum Seyctum Plenum. 173 
vestigations. In order to bring this phenomenon into 
bolder relief let us imagine that the isolation has already 
taken place and the new race isolated. In other words 
let us examine Fig. 31 (p. 169) and the data from which 
this is derived (pp. 170 and 176). Let us first fix our 
attention on the ordinate at 21. It contains only indi- 
viduals of the 21 -rayed race. But in 1894 a single ex- 
treme variant appeared, which, although it belonged to 
the 13-rayecl race, nevertheless had as many as 21 rays 
(p. 170). If the cultures of 1893 and 1894 had been 
more extensive the number of these extreme variants 
would obviously have been greater. For the ordinates 
20, 19, 18, etc., it is still more evident that individuals 
of both races can occur. 
If we choose plants which have 21 or more ligulate 
florets in their terminal inflorescences we cannot at all 
be certain that they all belong to the race which is be- 
ing sought. And if they are left to pollinate one an- 
other, or if their seeds are mixed in the harvest, there 
is small likelihood of the strain being pure. Amongst 
the majority of pure seed-parents a number of individ- 
uals of inferior value may exist and it is necessary to 
remove these as soon as possible, at any rate before the 
harvest. 
The possibility of doing this is afforded by the 
later flowers. By means of them a curve can be de- 
termined for each plant, and in this way values can 
be obtained which are independent of the chances in- 
separably connected with small numbers. The curves 
describing the separate parts of one individual are called 
its "part-curves.* 3 I have therefore plotted such curves of 
all the individuals selected at the beginning of the flow- 
ering period as having 21 and more rays in their ter- 
