Stout & Boas: STATISTICAL STUDIES IN CICHORIUM 385 
the plant E; for the year 1913, the number of flowers per head for 
the first day of bloom was 20.6 with a decrease of —0.064 per day; 
while for the year 1914 the average number of flowers for the 
first day of bloom was 20.7 with a rate of decrease of —0.032. 
The higher average in 1914 was due to a slower rate of decrease. 
To illustrate this point further we may take the plant (Ез X A) 
no. 7 (TABLES 8 and 9) in 1913 and 1914. In 1913 the average 
was 18.6 with a standard deviation of + 0.9; іп 1914, 19.0 with a 
standard deviation of + 1.7. Іп 1913 the blooming period was 
24 days; in 1914, 70 days. The averages are the same as for the 
plant E;, but the standard deviation is smaller for (Es X A) 
по. 7 in 1913. The values for the first day of bloom and the rate 
of decrease show that the plants are different in respect to flower 
number. In the plant (Ёз X A) ло. 7 the difference between the 
rate of change in 1913 and 1914 is not very great. In 1913 it was 
—0.045; in 1914, —0.053. The average flower number for the 
first day of bloom is, however, quite different for the two years. 
In 1913 it was 19.1; in 1914, 20.9. This together with the different 
length of blooming periods accounts for the differences in the 
values of a obtained for the plants Ёз and (Ез X A) по. 7. 
III. DETAILED PRESENTATION OF DATA BEARING ON 
I. RELATION OF LENGTH OF BLOOMING PERIOD TO RATE 
OF CHANGE 
One of the most obvious facts brought out by the data is that 
in plants showing a seasonal decrease the rate of decrease is less 
the longer the blooming period. The following correlation table 
(TABLE 17) brings out this fact very clearly. The plants used are 
three-year-old F; plants, of which there are data for 110 plants. 
For a further study of the relation of rate of decrease to length 
of flowering period these plants may be grouped as indicated. 
As there were rather few plants with short blooming periods, it 
Was necessary to include in the first group all the plants that 
bloomed less than 60 to 100 days. This group consisted of 16 
plants. There were only three plants that bloomed less than 60 
days, so these were left out entirely. In order to have a sufficient 
number of plants in the fifth group those blooming from 130 to 
` 150 days were here included. 
