1897.] NATURAL SCIENCES OF PHILADELPHIA. 187 



In northern regions, in southern Canada for instance, it flowers 

 in June. Under cultivation in eastern Pennsylvania, its flowering 

 season is during the first weeks in May. When the axillary buds 

 of the past season push into growth, some of them seem more vigor- 

 ous than others. Strange to say these vigorous branches are sud- 

 denly arrested at the second node, and, instead of a continuous 

 axillary growth, the cymose inflorescence follows. The flowering is 

 over by the first of June, and the white-berried fruit matures by the 

 first of July. But the weaker growths of the past season are not 

 arrested at the secondary node, but make a continuous growth until 

 the end of June, when the axial growth is also arrested and flowers 

 follow as in the earlier instances. These branches are flowering 

 while the earlier ones are maturing seeds. So suddenly is the axial 

 growth force arrested, that the two axillary buds at the base of 

 the axis, which in the condition of inflorescence becomes the 

 common peduncle, have the growth energy communicated to them, 

 and instead of remaining dormant to make side branchlets for next 

 year, start to form branchlets now. Some idea of the intensity of 

 the growth force, and the suddenness with which the energy was 

 diverted laterally, may be inferred from the fact that these axillary 

 buds, so suddenly called into development, will elongate and 

 form a pair of fully grown leaves by the time the blossoms in the 

 cyme have become fully developed. Except that the cyme, equally 

 with its axis, is somewhat weaker than the earlier ones of the season, 

 there is no material difference in the other portions of the inflores- 

 cence. The axillary buds at the base of the earlier blooming cymes 

 push into growth with as much vigor as those on the later blooming 

 branches, and some of these terminate in inflorescence, the flowers 

 blooming in August. The facts furnish excellent illustrations of 

 the influence of arrested or accelerated growth force in changing the 

 character and habits of plants. 



Another point I have taken occasion frequently to illustrate is 

 one which I believe to be wholly my own : — that leaves by no 

 means always originate at the node from which they seem to 

 spring, but from some indefinite point in the axis below. In this 

 Comus the sudden arrestation of growth which determines the 

 flowering conditions and the lateral divergence of the growth-en- 

 ergy* produces the union of a portion of the petiole with its axial 

 growth resulting in one of the branches of the cyme. In some cases 

 the arrested leaf-blade will form a bristle-like appendage an inch in 



