MORPHOLOGY OF COTTON BRANCHES. 13 



creased by the growth of more of the axillary buds into branches, 

 but in most cases the additional vegetative branches are produced 

 from extra-axillary buds that under other conditions would have 

 developed into fruiting branches. 



The nature of the differences between the two kinds of branches 

 must be understood before either the Mendelian reactions or the 

 environmental transformations can be appreciated. Though there is 

 nothing inherently improbable in the idea that the same character 

 may show both kinds of reactions, such cases would not be expected 

 under the Mendelian theory of heredity as a process of alternative 

 transmission of "unit characters." It would not be expected that a 

 character which behaved as a pure recessive in a Mendelian experi- 

 ment could be called forth by a change of external conditions. Yet 

 this possibility seems to be indicated by the variations that have 

 been observed in the brandling habits of cotton. 



RELATIONS OF FLORAL BUDS TO STIPULES. 



Though a casual examination of the cotton plant may appear to 

 support the theory that the fruiting branches are sympodial, there are 

 several facts that seem to forbid the acceptance of this view. The 

 relations of the floral buds to the adjacent parts of the fruiting 

 branches do not warrant the conclusion that the floral buds of the 

 fruiting branches correspond to the terminal buds of the vegetative 

 branches or of the main stalk. 



If the floral buds of the horizontal branches were homologous with 

 the terminal buds of the upright shoots, they should ave the same 

 symmetrical position in relation to the stipules. But instead of 

 standing midway between the stipules the pedicel of the floral bud is 

 always nearer to one of the stipules than to the other. The leaves of 

 the main stalk and vegetative branches have equal stipules, but on 

 the fruiting branches the stipules are generally unequal. The 

 inequality is especially pronounced in Egyptian cotton, where one of 

 the stipules is often more than twice as wide as the other. In all cases 

 the more enlarged stipule subtends the floral bud and frequently 

 shows a slight attachment to the base of the pedicel. 



A STIPULAR RIM ON FRUITING BRANCHES. 



Another peculiarity of the fruiting branches, shown especially in the 

 Egyptian cotton, is a narrow rim, or collar, that connects the bases 

 of the stipules, so that the base of the leaf may be said to encircle the 

 branch. This is not true of the leaves of the main stalk, where the 

 stipules become much more widely separated, with no indication of a 

 connecting rim. These differences may be ascribed to the fact that 

 the thickening of the joints of the fruiting branches is not symmetrical 



[Cir. 109] 



