I 2 5 
the Egyptian Cotton-plant. 
The equation is that of an autocatalytic chemical reaction and was 
originally formulated by W. Ostwald, who pointed out the similarity between 
growth processes and autocatalysis. T. B. Robertson (1908-1915) has 
elaborated the idea still further and prepared a series of tables for use in 
connexion with this equation. H. S. Reed (1920), working in California, 
has shown that the equation can be applied in many cases, and gives data 
for pear-trees and Helianthus so as to show the applicability to earlier 
published data on growth. 
The flowering curve of the cotton-plant is probably particularly suited 
for analysis along these lines. W. L. Balls (1915) has already shown that 
1-0 
X 
FiGr. 5. Flowering curves (flowers per plant per day) of Cotton-plants. Pilion. Variety test. 
Bahtim, 1920. The broken line indicates the familiar five-day mean flowering curve. (See also 
Fig. 6.) 
the flowering curve reproduces in its earlier stages the growth curves of the 
preceding month, and there is no doubt that the curve as a whole gives 
a very fair representation of the growth of the plant. The simplicity with 
I which flowering records can be obtained, the unitary character of the records 
independent of measurements either of length or of weight, and the large 
number of plants which it is possible to observe, make it possible to 
present data of reasonable accuracy and to smooth out irregularities due 
to individual plant variations. In most of the cases quoted below counts 
have been made on four hundred plants. 
The method employed in obtaining the curves is illustrated from the 
data given in Table I, following the methods usually adopted by the 
physical chemist. For a number of values of x and t the corresponding 
