M. Miiller on the Development of the Lycopodiaceae. 37 



rac to arise from the following circumstances : those cells which 

 were originally produced in the spore and became organically 

 connected with the spore-membrane^ belong peculiarly to this 

 last structure and form a special membrane upon the inner coat 

 of the spore as it becomes attenuated by its external prolonga- 

 tion_, for they have a flattened form and must be regarded as be- 

 longing to the spore-membrane only, since they are perfectly free 

 and distinct from the other cells of the " germ." In fact the 

 whole course of development exhibits it in this light. 



That these " bud-envelopes " were formerly regarded as actual 

 cotyledonary leaves, may be accounted for to a certain extent, by 

 the long time during which they remain visible upon the young 

 plant. Bat they cannot naturally be compared to cotyledons, 

 since they proceed from no embryo, and are in no wise different 

 from the leaves of the branches. But they have the same func- 

 tion on the young " germ," as cotyledonary leaves, to nurse, that 

 is, to defend the young buds of ramification, until they have at- 

 tained a self-sustaining degree of development. 



b. The buds of ramification. As soon as the " bud-envelopes " 

 unfold, i. e. have become turned back, the buds of the future 

 branches may be very distinctly perceived between them, oppo- 

 site to each other. Each occurs in the middle of the leaf, and 

 placed in such a manner that its side is turned toward the in- 

 ternal cavity of its enveloping leaf (fig. 6 a) . Therefore when by 

 their further unfolding the two buds become turned outwards in 

 opposite directions, a cruciform arrangement is produced with 

 the " bud-envelopes " (fig. 11). Every leaf which is inclosed in 

 the bud follows the same course. If we examine, with a view to 

 ascertain this, the bud represented in fig. 6, and unfold it, another 

 leaf presents itself (fig. 8), which, hollow and folded upon itself, 

 may contain yet more according as the bud has become deve- 

 loped, till at last we reach the axis on which the leaves are pro- 

 duced (figs. 9, 10). The development of these leaves I prefer to 

 describe as seen in the perfect plant. 



The unfolding of the leaves takes place according to the fol- 

 lowing plan : — 



1. Two "bud-envelopes" (fig. 5). 



2. Two ^rflwcA-leaves. These deviate 90° from 

 the first, and form a cross with them (fig. 11) a. 



3. Two leaves, which again cross the cross al- 

 ready formed. They stand therefore at an angle of 

 about 45° from the " bud-envelopes," and are at 

 this period the smallest leaves of the bud distin- 

 guishable by unassisted vision (fig. 12) b. 



