41 
The stomatal movement of Niphobolus adnascens is like that of 
Callipieris. In the (very moderate) thickening of the walls it suggests 
the Amaryllis type, but it is raised above and overlies the subsidiary cell 
sufficiently to cause the latter to hold the inner half, so that the outer 
half alone can move freely outward and backward . Its closure is effected 
by the ridge of entrance. The stoma of Nephrodium syrmaticum seems 
to be quite of the Amaryllis type; its dorsal walls are perpendicular to 
the surface. 
Another large "number of fern stomata are of the mechanical type of 
Medeola, or of that first described modification of it called the type of 
Mnium. These are broad stomata, with shallow guard cells the dorsal 
walls of which are rigid. The rigidity of the dorsal wall may be due 
to its own heaviness, as in Oleandra colubrina nitida, to local folds or 
thickenings, like those of Medeola, but less pronounced, as is the case with 
Scolopendrium schizocarpum, Vittaria minor , Polypodium ccespitosum and 
P. obliquatum; it may be due to its being struck only dorsally by the two 
anticlinal walls, as in Hymenolepis and P. sinuosum, or to being struck 
irregularly by more numerous walls, as in Davallia denticulata , Asple- 
nium muscefolium, A. macrophyllum, Adiantum mindanaoense, Vittaria 
minor, Prosaptia cryptocarpa, and others. Most ferns with these stomata 
have them slightly longer than broad, but exceptions are not infrequent. 
In the fertile frond of Loxogramnie conferta they vary from round 
stomata to those which are 59 p. long by 74 p broad, and in Asplenium 
macrophyllum from some which are longer than they are broad to exam- 
ples which are 24 p long by 33 p broad. The movement of these stomata 
is illustrated by Niphobolus varius and Prosaptia cryptocarpa. Measure- 
ments on the former are: 
Open. In -A- KN0 3 
Width of stoma 
microns. 
... 34 
34 
Width of ridge of entrance... 
do 
3 
0 
Width of ridge of exit 
do 
... 8 
5 
Measurements on P. cryptocarpa 
are : 
Open. 
[n^ 5 KN0 3 
In i KN0 3 
Length 
microns... 45 
45 
Width of stoma 
do 45 
. 
45 
Width of pore 
do 5. 5 
3. 5 : 
2 a 
In some of these stomata, closure is still less complete. Thus, in Loxogramme 
conferta the open pore is 14 p wide, and closes only to 8 p. That of L. iridifolia 
remains open 4 p after three days in darkness, but closes to 0.5 p if plasmolyzed. 
The stoma of Scolopendrium schizocarpum is 68 p long by 53 p broad when closed; 
each guard cell is then 26.5 p broad, or very nearly that, but only 10 p in depth. 
Some species have still shallower guard cells. In Drynaria quercifolia and 
Photinopteris, but not in Dryostachyum, the lumen in median cross-sections is 
a Plasmolyzed. 
