122 
Prescott . — The Flowering Curve of 
successful in the case of the Egyptian cotton crop. Flower counts, boll 
counts, and growth data, all first inaugurated by W. L. Balls, are now 
extensively used in Egypt. Since the season of 1917 a large number of 
flowering curves have been obtained at the Bahtim Experimental Station 
relating to cotton under many different conditions of experiment. Although 
the intensity curve of flowering (flowers per plant per day) is of greater 
interest to the physiologist, yet to the agriculturist a summation curve 
represents much more satisfactorily the actual condition of the plant at any 
given moment, and these curves have been used at Bahtim since the present 
Fig. 2. Flowering curve of Cotton, Bahtim, 1920. Sakellaridis, plants topped and water 
restricted in August. 
series of observations was started. One striking feature of the summation 
curve (total flowers per plant up to the date given) was the fact that the 
irregularities were more or less smoothed out and a characteristic S-shaped 
curve was always obtained. Other data published by W. L. Balls (1912) 
and B. G. C. Bolland (1917) gave similar summation curves. 
It will be seen from the analysis of some of the typical records that 
this summation curve can be expressed with considerable accuracy by the 
following equations : 
% = kx(a-x) or lo °r 
=K(t-t x ), 
