FILICINEM, 



All 



sided^ (Fig. 336, A,B). The two rows of segments here form an elevated vegetative 

 cone, at the base of which the rudiments of the leaves first appear at the height of the 

 fourth or fifth segment. The two edges of the apical cell are directed upwards and 

 downwards (on the obliquely ascending shoot). The relationship of the leaves to 

 the segments has not yet been entirely made out. The two leaves of each pair arise 

 obliquely, one above, the other below, and alternately right and left where the pairs 

 cross obliquely, by the outgrowth of zones of cells, each of which embraces about a 

 fourth of the circumference of the stem. Divisions then take place in these cells 

 which are directed obliquely upwards and downwards, and a row of apical cells is 

 thus formed, by means of which the growth of the leaf is continued (Fig. 336, A). 

 The branching of the shoot is effected by a second two-edged apical cell being 

 formed from the youngest segment (Fig. 335, C, B), a wall being developed in it 

 which is convex to the existing apical cell and which intersects the primary wall 

 below. The two shoots which are thus formed grow right and left of the previous 



Fig. 336. —Apex of the stem oi Selaginella MarteMsu (d^har Pfeffer) ; A longitudinal section of the end of the stem with 

 the first rudiment of the leaves ; B apex of the stem seen from above ; C formation of an apical cell seen from the side ; 

 D the same seen from below. The primary walls of the segments are denoted by darker lines ; the segments themselves 

 are numbered with Roman figures. 



direction of growth, and all the successive branchings take place in one and the 

 same plane. 



The Roots. All the species of Selaginella possess true roots ; but in some, 

 as -5". Mariensii and Kraussiana, they arise on a structure which Nageli calls the 

 Rhizophore, and which has no root-cap. In S. Kraussiana the rhizophores spring 

 from the dorsal side of the stem, nearly at the base of the weaker of each pair of 

 branches, curl themselves round it, and then grow downwards; it is only rarely 

 in this species that two of these organs arise near one another. S. Martensu\ on the 

 other hand, forms at each branching two rhizophores, one on the dorsal and one on 

 the ventral side (the plane which passes through them is perpendicular to the plane 

 of branching), but usually only the ventral one undergoes further development, while 

 the dorsal generally remains in the form of a small protuberance. The rhizophores 



' [Treub has shown (Recherches etc. sur le Selaginella Martensii) that the form of the apical cell 

 is very variable ; it is sometimes two-sided and sometimes three-sided in branches of the same plant.] 



