362 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
PRESENTATION OF DATA FOR FLOWER NUMBER 
IN CHICORY | 
I. GENERAL SURVEY OF THE KINDS OF VARIABILITY PRESENT 
I. PARTIAL VARIABILITY 
A. Intraseasonal partial variability. 
Thecollection of random data on successive dates from individ- : 
ual plants reveals that, as a rule, there is a marked decrease in 
flower number per head as the period of flowering advances. 
Differences in number per head appear according to the stage of 
development of the plant as a whole. 
The seasonal performance of a plant, as shown in such tables 
as 1 and 2, indicates that the number of flowers per head in heads 
as they appear from day to day is much higher during the early 
period of bloom than in the last days of bloom. This is indicated 
by both the daily range and the daily average. The change, 
however, is rather uniform and progressive as the season ad- 
vances. 
Partial variability, or variation among the apparently homol- 
ogous heads produced by a single plant, is therefore seen in the 
range of the number per head; in TABLE 2 the range is from 12 to 
23. But the daily data show that the range of values and the 
average value shifts from day to day. The variations from day to 
day are not therefore solely chance variations, since certain 
elements of differentiation appear. 
The totals of all heads with the same number of flowers give 
what appears as a chance distribution. The chance collection of 
data for any period of time, as the first ten davs, the second ten 
days, etc., would also give general summaries that would appear 
as chance variations; that such data do not adequately represent 
the individual seasonal performance is, however, very obvious. 
Random collections would hardly reveal the presence of intra- 
seasonal variation; it is only the tabulation and computation of 
data for individual days from individual plants that clearly 
brings out such facts. 
For the sake of completeness, there are given with the tables 
values whose significance will become clear later on. It is suff- 
cient to point out here that a is the computed flower number for 
