Stout & Boas: STATISTICAL STUDIES IN CICHORIUM 437 
also been presented (TABLES 31, 32, and 33) and discussed as 
illustrating (1) increase in flower number per head during a period 
of growth and (2) the fact that values for the second period of 
growth are lower than those for the first. 
For judgment of the general performance of this race, there 
are data for 35 sister plants and for 15 of these there are also data 
from the growth of the second period, all of which are given in 
TABLE 53. 
For the period of first growth, it is seen that values for a range 
from 15.5 to 18.3 with an average of 16.9 + 0.62. The values 
are very uniform and are decidedly low when compared with those 
of the semi-dwarf race (race no. 1) considered above. The most 
decided variability of this race is seen in values of rate of change 
in flower number; these range from —0.048 to +0.018. These 
differences in rate of change did not seem to involve any differ- 
ences in vegetative habit of growth, in the grouping of flower 
heads in clusters, or in the total number of heads produced. 
Reference has already been made to the general performance of 
the growth of the second period and to the evidence that the values 
for such growth are as a whole lower than those of the earlier 
growth. : 
In its ancestry, this race descended from an Fi plant {(A X 
Ex) по. 9] from which по data were obtained. 
For the parent selected for the Ез, (А X Е») —9-no. 5, the 
value of а was 16.5 and that of b was —0.022. Тһе parent of the 
Е, (A X Ex) —9-5 —no. 12, was one of 13 sister plants whose 
values for a ranged from 15.2 to 18.0, averaging 16.6 with a stand- 
ard deviation of +0.86; its a value was 17.7 (high for the genera- 
tion) and its b, —0.024. 
As to value of a, the line of parentage has therefore exhibited 
rather medium values. 
Considering the value of a for the first period of growth, the 
values are quite characteristic for the line of descent as a whole 
(TABLES 27 and 53). 
D. Characteristics and history of а semi-robust brittle-stemmed 
race (race 4). The plants of this race are coarsely and somewhat 
sparsely branched, the branches are thick and very brittle and 
bear such small leaves as to appear almost leafless. The thirty 
