248 HOFMEISTKR, ON 



they root here and there, and are traversed by a vascular 

 bundle. The apical cell of the terminal bud is always 

 two-sided in N. undulata. On the thicker stolons of 

 N. splendens it appears to be frequently three-sided. In 

 N. undulata it first assumes this form when the apex of the 

 runner begins to form a knob. Within the swelling mass 

 of parenchyma the central vascular bundle, which has 

 hitherto been simple, becomes branched (PI. XXXIV, 

 fig. 1). The bundles are henceforth arranged in a circle 

 concentrical with the periphery of the knob. 



As far as my observations extend, the vegetation of 

 the terminal bud ceases with the complete formation of 

 the knob, which is about an inch long.* The arrange- 

 ment of the cells admits of the observation of their mode of 

 cell-multiplication, if followed out in the same manner as 

 in the end of the stem of Aspidium filix-mas. The con- 

 tents of the cells, as well as those of the numerous rudi- 

 ments of withering scales by which they are surrounded, 

 become transparent. The knob sends forth fresh adventiti- 

 ous buds, which originate in numbers on its lateral surfaces 

 (PL XXXIV, fig. 2). Soon after the development of these 

 shoots the knob decays. 



Polypodium, Niphobolus. — The species of Niphobolus, 

 which I have examined (JV. rupestris and N. chinensis), as 

 well as several foreign species of Polypoclium {aureum,puncta- 

 tum, cymatodes), all exhibited the two-edged form of apical 

 cell answering to the bi-linear frond-arrangement. In Poly- 

 podium vulgare it was otherwise. Here the terminal bud, 

 when viewed from above, exhibits sometimes the form of the 

 cell of the first degree and the arrangement of its next deriva- 

 tives as in Aspidium filix-mas (PI. XXXIV, fig. C) ; some- 

 times (and most frequently) the two-edged form of the upper 

 surface of the apical cell (PL XXXIV, fig. 5) ; sometimes 

 forms which may be looked upon as intermediate between 

 the two, inasmuch as the free outer wall of the cell of the 

 first degree has the shape of a triangle, whose sides are 

 more than three times the length of the base. Deviations 

 from the typical bi-linear frond-arrangement are not un- 



* This is opposed to Kunze's statement. He describes the further develop- 

 ment of the apex of the bud, 1. c, p. 882. 



