330 Bower . — The comparative examination of the 
tion of conical cells ( o ). On the circinate phyllopodium 1 thus 
formed, which has a marginal series of cells continuous on 
either side to its extreme base, the pinnae begin to make 
their appearance as monopodial branches, ranged on the 
lateral flanges or wings which grow out from the marginal 
series of cells ; the first-formed pinnae originate distinctly 
below the apex of the phyllopodium (Fig. 32), and alternate 
on opposite sides of it ; the marginal series of cells is con- 
tinuous also over their margins, but no initial cell is to be 
seen at their apices. On the other hand, the apex of the 
phyllopodium may be seen to have a clearly defined apical 
cell, even after a considerable number of pinnae have been 
formed, and this in itself would preclude the idea of a 
dichotomous branching ; Prantl 2 has described the branching 
of the leaves of the Hymenophyllaceae as c purely dichoto- 
mous ’ ; this is certainly not the case for Trichomanes radicans. 
I have also made observations as to the persistence of the 
apical cell of the phyllopodium, a point which Prantl left 
undecided from want of suitable material. In a leaf which 
had already formed sixteen pinnae the apical cell was still 
clearly recognised, while in leaves respectively with twenty- 
three and with thirty-two pinnae no apical cell could be 
seen. It is probable that there is no strict time when its 
identity is lost, but that ultimately it undergoes a T division 3 
(which I was fortunate enough actually to observe in Tricho- 
manes reniforme , Fig. 33), and so passes over into the 
marginal series 4 . It may be added that the monopodial 
type of branching occurs not only in the phyllopodium, but 
also in the pinnae, and in one case it was clearly recognised 
that the eighth pinnule originated in a monopodial manner, 
distinctly below the extreme apex of the pinna. Subsequently, 
however, both in the phyllopodium and in the pinna the 
1 This term has been adopted for the rachis or main axis of the leaf, whether 
branched or not. Phil. Trans. 1884, II, p. 569. 
2 1. c. p. 14. 
3 Compare Sadebeck, Entw. u. Wachsthnm d. Farnblattes, p. 10, and Fig. 6. 
4 It is not inconsistent to regard the apical cell itself merely as a special cell of 
the marginal series. 
