62 THE COTTON PLANT IN EGYPT CHAP. 



steadily till the winter. The form of the later part of the 

 curve is usually modified by subsoil water effects, either 

 through root-asphyxiation, or by continuously shallow soil 

 which accentuates thermo-toxic effects through water- 

 shortage. 



The actual form of the curve is also determined by the 

 branching-habit, since the flowers are produced by special 

 branches. For our purpose it is not worth while to enter 

 into detailed discussion of these branches and their effect 

 on the utility of the plant; they have been closely 

 investigated by Mr. Leake.* Their general effect on the 

 flowering curve may be seen best in second generation 

 hybrids ; continuous growth without lateral mynopodial 

 branches, resulting in a straight stem bearing sympodial 

 flowering branches only, produces a flowering curve which 

 remains low and without modes throughout the season. 

 The substitution of discontinuous growth-habit in com- 

 bination with the same habit of branching, cuts but a 

 resting-period from this curve. Discontinuous growth 

 with free vegetative monopodial branches at the base of 

 the stem, which in their turn produce sympodia, causes 

 the flowering curve to run up to a high mode, then to fall 

 rapidly to zero, and to rise again in the autumn. Similar 

 branching to this, but combined with continuous growth- 

 habit, builds up an enormous flowering curve, which rises 

 steadily to a maximum (not infrequently amounting to 

 25 p.p.p.d. flowers), and then descends to the winter. A 

 total production of five hundred flowers in a month is 

 common among plants possessing this last combination 

 of habits. t 



Confining our attention again to the usual Egyptian 

 type of flowering curve, the normal form of this may be 

 affected by the environment through the growth-processes, 

 but it is frequently important to remember that a normal 

 form exists, since these distortions often serve as useful 



* Leake (2), (3). 



