41 
The stomatal movciiicnt of NiphohoJus adnascens is like that of 
Callipteris. 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 innci' half, so that the outer 
half alone can move freely outward and backward. Its closure is (;trectctl 
by the ridge of entrance. The stoma of Nephrodkwi syrmalicum seems 
to be quite of the Amaryllis type; its dorsal walls arc perpend icidar to 
the surface. 
Another large number of fern stomnta are of the moclianical ivpc of 
Medeola, or of that first described modification of it called the type of 
Mnium, These are broad stomata, with shallow guard colls the dorsal 
walls of which are rigid. The rigidity of the dorsal wall may be due 
to its own lieaviness, as in Oleandra coluhrina nltida, to local folds or 
thickenings, like those of Medeola, but less pronounced, as is the case with 
Scolopendrium schizocarpum, Vittaria minor, Folypodinm cwi^pifosnm and 
P. ohliqiiatum; it may be due to its being struck only dorsally by the two 
anticlinal walls, as in Hymen olepvi and F, sinuosum, or to being struck 
irregularly by more numerous walls, as in Davallia dcnilcuhinj AspU- 
nium muswfolium, A. macro phyll am, Adiantum mindanaocnse, 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 Loxogramme conferta they vary from round 
stomata to those which are 59 fx long by 74 /a broad, and in Asplenium 
macrophyllum from some which are longer than they are broad to exam- 
ples which are 24 fx long by 33 jx broad. The movement of these stomata 
is illustrated by Niphoholus variiis and Prosaptia cryptocarpa. Measure- 
ments on the former are: 
open. In ~ KNO3 
Width of stoma microns.... 34 34 
Width of ridge of entiiince do 3 
Width of ridtro of oxit do 8 5 
^fcasuTfinonts on P. erijptocarpa aro: 
OiK'ii. In **;^'* KNOs In J^ KXO, 
Length microns.... 46 45 
AVidth of stoma do 45 45 
Width of pore do 5. 5 3. 5 2» 
In =,ume of these stomata, closure is still less cnmplote. Thus, in Loxogramme 
conferta the open pore is 14 fi wide, and closes only to 8 /*. Tliat of L. iridifolia 
remains open 4 fi after tliree days in darkness, but closes to 0.5 /i if plasmolyzed. 
The stoma of Scolopendrium schizocarpitm is flS /x long by 53 fi broad when closed; 
each guard cell is then 26.5 /i broad, or very nearly that, but only 10 fi in depth. 
Some species have still shallower guard cells. In Drynona qnrrcifoUa and 
Phothwpfcris, but not in Dryosiachyum, the lumen in median cross -sect ions is 
■ PlaBDiolyzed, 
