38 M. Miiller on the Development of the Lycopodiacese. 



4. This arrangement does not long persist, for \ I / 

 two new leaves arise between the last two c, and —i(—- 

 affect the position of the remainder, so that a is /'\ 

 pushed aside to the extent of 45°. c stands almost * '^ 

 exactly at an angle of 90° with the bud-envelopes 



(fig- 13)- M^^ 



5. Then two more leaves appear in each bud ~/7v\~ 

 which deviate almost equally about 90° d. i ^ ^ tv 



The alternation of the first two leaves a b may already be re- 

 marked here, whereof b is placed higher up on the axis of the 

 branch than a. Both are attached to the lower side of the axis, 

 and are the larger leaves, c and d, on the contrary, are deve- 

 loped upon the upper side of the axis of the branch, and are here 

 (in L. denticulatum), as almost universally in Selaginella, smaller 

 than the preceding. Spring calls them/o/w intermedia. 



Between the last and first leaves lies the axis of the branch, 

 which now becomes elongated, while in the next place two other 

 larger leaves become visible, whereupon two folia intermedia 

 appear on the upper side, &c. 



Four series of leaves therefore are now distinctly visible upon 

 the axis of the branch, two above and two below. Of these four 

 series two on one side always correspond so with each other, that 

 first a large leaf is situated on the under, and a folium interme- 

 dium at some distance on the upper side. But if all four series 

 are now compared, a folium intermedium is normally opposite a 

 large leaf situated on the other (under) side (figs. 15 — 18) ; con- 

 sequently two series of leaves always alternate wdth each other. 



The two opposite buds developing in this manner, the germi- 

 nating plant becomes bifurcated. But one of the buds is some- 

 times abortive, and then of course there is no bifurcation ; the 

 single bud developes into a branch, and this subsequently under- 

 goes a bifurcate division (PL II. figs. 18, 19). 



c. Accessory organ. I come now to an organ which is con- 

 tained in the terminal bud and contemporaneously formed, and 

 which, so far as I know, has never hitherto been observed. It 

 appears to me that it must be of importance to the plant, since 

 its occurrence is constant. 



It is a body, usually pyriform, composed of a number of deli- 

 cate, transparent, parenchymatous cells. It is consequently 

 bellied out at its base and attenuated into a neck above (PI. III. 

 fig. 1). It is compressed on two sides, but in such a manner 

 that its borders are not acute, but rounded (fig. 2) . The borders 

 are entire, and the apex alone, which is always truncated, has 

 the uppermost cells irregular and more or less rounded. Within 

 them are parenchymatous cells usually smaller, normally hexa- 



