40 
In my paper on the mechanism of stomata, just cited, I showed that 
there was diversity even among our few Polypodiacece in the eastern- 
United States; the range in the Philippines naturally is much wider in 
all respects. The turgor of the guard cells has an exceedingly wide 
range. In Pteris opaca, it is the same as in the epidermal cells, or 
(using a familar ellipsis) 0.3 to 0.4 normal potassium nitrate. In 
Leptochilus heterophyllus, it is 0.5 normal potassium nitrate in the guard 
cells, but only 0.4 normal in the epidermis. In Loxogramme iridi folia, 
plasmolysis of the guard cells begins in 0.5 normal solution. In Pro- 
saptia cryptocarpa and Poly podium dolichopterum, the turgor is 0.7 
normal, that of the epidermis of the latter being the same; and in Nipho- 
bolus varius .(other Niphobolus species are not very different) the pore 
closes in a normal solution of potassium nitrate, but plasmolysis is doubt- 
ful even in this concentration. In Niphobolus all neighboring cells of 
the stoma plasmolyze before the pore appreciably begins to close. 
Probably a majority of the ferns here and elsewhere in the world are 
similar to Dennstcedtia punctilobula in their stomatal mechanism al- 
though in most of them the development of the ridge of entrance is less 
excessive. Representative of these are N ephr odium spar sum, Leptochilus 
heterophyllus, Pteris opaca and Polypodium dolichopterum. The stomata 
of this type are considerably longer than they are broad, and are struck 
by anticlinal walls only near the ends; usually, in fact, only near one 
end, because of the mode of origin of the stoma. Measurements of the 
stomata of N. sparsum are : 
Width of stoma. 
microns ... 
Open. 
36. 5 
In -5^- KNO,) 
N 
35 
Width of ridge of entrance 
3 
0 
Width of guard cell 
do..—— 
16 
17. 5 
Width of pore 
do 
4 
0 
The stoma of Polypodium dolichopterum does not quite close. Measurements on 
it are: 
Open. In ~-KN0 3 In KNO s 
Width of stoma microns ... 46 45 45 
Width of pore do 5 0. 5 0. 5 
The stoma of Pteris opaca widens 1 y while the pore opens 3 y. 
Callipteris corcbifolia is not very far from this type, opening chiefly by a 
swinging outward of the ridge of entrance; but its width does not change. 
Measurements on it are : 
Length 
microns.... 
Open. 
81 
in ir KNOs 
82 
Width of stoma 
....: do 
35 
35 
Width of “pore” •, 
do. 
12 
5 
Width of ridge of entrance 
— dO...:.... 
6 
0.5 
Some of the stomata close completely. 
