Copeland . — The Mechanism of Stomata. 353 
Of the Gy mnosperms enough has been said. And of the 
Glumiferae it need only be stated that in the four Scirpeae 1 
I have examined — Cyperus rivularis , Kunth, Fimbristylis 
capillar is, Gray, Scirpus Cyperinus , L., and 5. polyphyllus , 
Vahl — median cross-sections show the thickening typical of 
other sedges. The stomata of Jnncus acuminatus 2 , Mx., are 
mechanically more like those of sedges than like those of 
Luzula , in spite of their curved dorsal wall. In some species 
of Luzula , Westermaier finds the thin polar areas in surface 
view, but they are invisible in my L . campestris , DC. 
The stomata of the Liliaceae and their relatives have the 
one common character that they are large, and therefore 
convenient subjects of study, so that they were in almost 
exclusive use by the earlier investigators. The same character 
makes them an excellent subject of study from the mechanical 
side. That there is no particular type characterizing the 
Liliaceae, as might be inferred from references by Schwendener 
(1889) and Westermaier, is perfectly evident from the illustra- 
tions I have already used — Medeola , Lilium , Smilax , Dracaena , 
Polygonatum , and Allium. The enumeration of more kinds 
emphasizes the diversity. Disporum lanuginosum has the 
stomata broad, but also deep, combining the characters of 
Amaryllis and Achillea . The movement is mostly by the 
inner half, and is facilitated by the contour of the neighbouring 
cells inside the ends of the guard-cells (Fig. 47 ). Uvidaria 
perfoliata , L., has clumsy stomata, nearest Helleborus. Those 
of U. gran diflora, Smith, suggest Iris. Erythronium A meri- 
canum , Ker., is nearer Achillea than any other type. Clintonia 
umbellata , Torr., has a mixture of Amaryllis and Mnium 
characters. The same is true of Smilacina racemosa , Desf., 
while Maianthemum Canadense , Desf., is nearer Amaryllis . 
Convallaria majalis , L., also has them of the Amaryllis type 
on young leaves ; on leaves a year old they are thickened 
so as to resemble those of Helleborus , but are little, if at all, 
movable. Those of Myrsiphyllum are not distinguishable 
1 Cf. Schwendener, 1889, p. 71. 
2 Schwendener, 1889, p. 77; Westermaier, 1 . c. p. 78. 
