366 SEMI-CENTENNIAL OF TORREY. BOTANICAL CLUB 
the first day of blooming, 6 the calculated rate of decrease per day, 
and ¢ the number of days the plant was in flower. [o] represents 
the average flower number of the plant, calculated as are all the 
other values, from data collected throughout the flowering period. 
Exceptions to the general rule of seasonal decrease occur. 
One of these is indicated in the performance record given in TABLE 
3. The marked feature here is the decided uniformity in both 
range and average number of flowers per head throughout the 
entire period of bloom. 
The plant here considered (TABLE 3) bloomed for a period of 
two months. The total number of heads counted was 248. 
The partial variability seen in the range of 1 5 to 20 was quite 
indiscriminate and coéxistent as to time. As the season advanced 
there was no appreciable change and the computed value for the 
rate of decrease is 4-0.004, a slight increase. 
Data of another plant showing no intraseasonal decrease are 
presented in TABLE 4. Неге there is, as in TABLE 3, no noticeable 
change in the general average or range from day to day, except 
for a few irregularities at the beginning and end of bloom in which 
the values usually obtained are reversed ; the very lowest numbers 
per head appearing on the first two days of bloom. 
In a few cases there is a decided though small increase from 
the beginning to the end of the season. The greatest increase 
observed was +0.025. In all these cases the plants had a low 
flower number throughout the season. TABLE 31 gives data for 
one of these plants. : 
А further variation in seasonal performance is shown by data 
of TABLE I5. Here there is a marked decrease both in the range 
and in the average of flowers per head, but the lower numbers of 
the range remain quite the same throughout; the shifting involves 
chiefly the higher numbers. 
B. Interannual partial variability. 
The collection of data from the same plant in successive years 
makes possible a comparison of the performance of an individual 
in different years in which the seasonal and growth conditions 
may be different, and in which the different ages of the plant may 
also give differences in vigor involving differences in time of 
blooming, all influencing the performance of the season. 
