Dr. A. Braun on the Veyetuble Individual. 377 



the manifold relations under which sexual division of generation 

 occurs in ])lants. 



Dioecious relations may occur without alternation of genera- 

 tion when, in fact, the tiowcr has a terminal intiorescence and 

 no branches, or only unessential ones, — when, therefore, as it 

 is usually expressed, it is " uniaxial," as e. g. in Rubus Cha- 

 mcemorus, Lychnis, and Viscuin. Much more frequently, how- 

 ever, division of the sexes occurs in plants which at the same 

 time have a cyclical succession of shoots (alternation of genera- 

 tion), — a succession which each of the two heterogeneous stocks 

 passes through independently, and not alwayii pari passu. This 

 is a circumstance which must not be neglected in considering 

 the differences of habitus in male and female flowers. Thus, in 

 Mercurialis the female plant bears flowers even on the second 

 axis ; in the male plant, however, — if I do not misunderstand 

 the inflorescence (a spike composed of small glomerules), — this . 

 flrst occurs on the third. In Cartx dioica, vice versa, the male 

 plant flowers in the second line and the female in the third*. 

 In other dioecious plants, on the other hand, the male and female 

 flowers appear in the corresponding generation : e.g. in the 

 second, Stratiotes, Empetrum, and Taxus; in the third, Salix, 

 Populus, Myrica, Cannabis; in the fourth, Phoenix. In Hemp, 

 the extremely heterogeneous appearance of the inflorescence of 

 the male and female plants does not depend upon a division of 

 the flowers of the two sexes among difiierent axes, but upon the 

 production of numerous unessential peduncles in the male inflo- 

 rescence f. 



Monoecism necessarily presupposes a succession of shoots 

 (alternation of generation) ; in the simplest case at least for one 

 of the two sexes, as both cannot be united in the same terminal 

 flower; but, vice versa, both may easily appear in determinate 

 (equal or unequal) degrees of ramification. The most important 

 circumstance to be considered in monoecious relations, consists 

 in both the sexes {i. e. the shoots which bear them) occurring 

 either subordinately or coordinately|, for one either arises out of 



* The second axis, wliich is a complete dwarf or a mere bristly spine, 

 bears the so-called ' nrceolns.' in the axil of which the female flower is 

 placed, as the third mcml)er of the succession of generations. 



t The female flowers are placed at the sides of the primary branches 

 as branches of the second degree. In the same jdace where one single 

 flower occurs in the female ])lant, a furcately ramified inflorescence is found 

 in the male, produced l)y branching out of the two bracts of the original 

 flower. 



X Both these cases doubtless occur in the animal kingdom ; the first 

 probably in Alcyortclln. where the stock is said to be comj)Osed partly of 

 males and partly of females. .\s the stock is here formed by individuals 

 rontinuallv shooting out of earh other, one sex must shoot out of the 



