420 “ SEMI-CENTENNIAL OF ToRREY BOTANICAL CLUB 
From data taken on an average of every third day throughout 
the period of bloom, it often appears, as may be illustrated in 
TABLE IO, that a well-pronounced maximum or mode is in evidence. 
In this particular instance there are 86 heads with 19 flowers per 
head, and about this mode there is quite a regular chance distri- 
bution. In other cases, the distribution is less regular and a mode 
is less pronounced. In no case, however, has there appeared evi- 
dence of a strongly bimodal distribution. Of course, data on all 
heads blooming on a plant would perhaps bring out the modal 
number more prominently. The collection of data during only a 
part of the blooming period would, of course, give quite different 
modes for any plant which exhibits a rate of change. 
The range and distribution of the modal values for various 
groups of plants are given in TABLE 40. Several points are clearly 
indicated. The range of individual variability of modal numbers 
is rather wide and extends from 14 to 22. Interannual partial 
variability exists, as shown in the first section of the table, which 
presents data of a single generation in the first, second, and third 
years of growth. The distribution is somewhat irregular and the 
number of plants observed is not as large as one might wish, but the 
evidence is quite clear that the mode for a plant actually shifts to 
higher values at least during the first three years of growth. 
TABLE 40 
DISTRIBUTION OF MODES FOR FLOWER NUMBER PER HEAD FOR INDIVIDUALS OF 
VARIOUS GENERATIONS AND LINES OF DESCENT 
a Distribution of modes Number | Average 
an | of plants| mode 
14 15 16 т т8 I9 20 2r 22 
Е: First year...... 31-9 b РН. 38 18.4 
Second year.. = 4 21.26 L1 Вр 52 19.1 
Third year...... H 4 т 30d £r 15 | 1X 63 19.5 
Fs and Е; 
(X ae и | od Б юра лз 31 18.8 
(А X Eabh... 2 | 4t | 31 | 4i 3 118 16.0 
(Ез X А)-то- ече Se ВА тты 3 16.8 
ummary... 2 | 51 | 62 |130 | 20 | 23 пра раци 208 16.8 
Ra tO. ууш. у: ІІ 531221 771241 то 9 2l. 79 17.4 
The second section of the table presents data for the F; and 
F, generations of three main lines of descent in the first year of 
