580 FILICALES 
of the sporangium to the receptacle, and that the distal part of the annulus 
is directed obliquely towards its apex. This being the case for all the 
sporangia, the free action of the annulus on dehiscence is assured for each 
individual sporangium; this may be compared with No. 95 of Hym. dilatatum. 
The stomium in 7%. radicans is of very simple construction: in the last of 
the drawings it is shown in surface view, with the slit of dehiscence gaping 
between the two cells. Comparing this with No. 96 of Hym. dilatatum, we 
see again that Zrichomanes 
is constructed on the same 
general plan, of which it ap- 
pears as a simplified edition. 
The origin of the spor- 
angium has been followed 
by Prantl! in Zyichomanes 
speciosum, with which that 
of Hymenophyllum agrees in 
essentials. The parent cell 
has a square base, and grows 
out into a papilla, with seg- 
mentation according to the 
usual Leptosporangiate type; 
but it is important to notice 
that the first segmentation 
strikes the basal wall of the 
parent cell (Fig. 326), a con- 
Fic. 326. dition which is seen in the 
Trichomanes speciosum, Willd. (=T. radicans), transverse MASSIVE sporangla” of the 
i i : ‘ : A . ‘ : 
eel thts Pons showing early segmentation of the Simplices rather than im the 
° more advanced Ferns. 
The comparison thus suggested with the Fern-types which have large 
sporangia is borne out by the facts which follow from enumeration of the 
spores produced. The Hymenophyllaceae show among their species a wider 
range of number of spores per sporangium than has been noted for any 
other family of Ferns: while certain of their species approach, or even equal 
the high numbers of the Gleicheniaceae, Schizaeaceae, and Osmundaceae, 
in others the number is distinctly low: it will be seen that the species of 
LHymenophyllum give for the most part a higher output per sporangium than 
Trichomanes.2 The typical number for A. Zunbridgense was found to be 
256-512, and for A serzceum 256, while that of AZ. dilatatum and IVilsont 
was 128; but for six species of Zyzchomanes examined the typical numbers 
varied from 32 to 64. Zrtchomanes reniforme, however, which is in many 
respects an isolated and peculiar species, has the typical number of 256, 
thus corresponding to Mymenophyllum rather than to its own genus. 
Seeing that in Tvichomanes the usual output per sporangium is lower 
1 Hymenophyllaceen, p. 38. 2 For full details see Stadées, iv., p. 64. 
