THE HIGHER CRYPTOGAMIA. 227 



with that above described in Pteris aquilina, and the mode 

 of ramification of the blade of the frond is the same as in 

 the latter plant (PL XXVI, fig. 8). 



The germ plant of Aspidium filix-mas developes its second 

 frond at a distance of about a third of the circumference of 

 the stem from the first. At the point of junction of the 

 vascular bundles of the first frond and of the first root, 

 there is formed a vascular bundle, which, after traversing 

 the axis for a short distance, bends off into the second 

 frond (PI. XXVI, fig. 13). The second root is developed 

 from that part of the vascular bundle which is situated in 

 the stem, and at some little distance beneath the place of 

 insertion of the second frond. The third frond diverges 

 from the second, and the fourth again from the third, at 

 about 120° to the right, so that the fourth stands vertically 

 over the first. At the bending-point of the vascular bundle 

 which passes out of the longitudinal axis of the stem into 

 the second and succeeding fronds, there is produced a 

 vascular bundle, which, after passing along the axis of the 

 stem for a short distance, bends off into the next younger 

 frond. Transverse sections of the stem exhibit only one 

 vascular bundle (PI. XXVI, fig. 12). The length of the 

 stem between each two of the first four, five, or six fronds, 

 is much greater than between two of the subsequent 

 fronds. 



The thickness of the stem increases suddenly and con- 

 siderably above the fifth or sixth frond. This rapid growth 

 in thickness takes place whilst the next younger fronds, the 

 seventh to the tenth, continue in the state of buds. Owing 

 to the vigorous and rapid peripheral development, the 

 apical region of the stem becomes almost a flat surface, in 

 the middle of which the outermost point of the stem pro- 

 trudes (PI. XXVI, fig. 15). Around it the youngest 

 fronds are arranged spirally. Henceforth the end of the stem 

 retains this form (PL XXVI, fig. 19 ; PL XXVII, figs. 3, 4). 



The flattening of the terminal bud depends upon the 

 fact that the superficial cells of the conical cellular mass 

 divide repeatedly by septa parallel to the chord of the 

 arcuate free outer wall — (a mode of cell-multiplication 

 which increases continually from the apex of the cone to its 



