272 de Fraine . — The Morphology and Anatomy of the 
the culture plant (f) the cuticle is markedly thinner than in the other forms ; 
the epidermal cells are also smaller, and no trace of internal cuticle 
was seen. 
The cells of the lower epidermis show characters essentially similar to 
those of the upper, except that the ridging of the cuticle is slightly more 
pronounced in the case of the Main bank, narrow-leaved lateral, and mud 
forms, while in the sand plant the ridging is much more marked (Text- 
fig. 21, K), a fact which is probably to be correlated with the reflection from 
the sandy surface. 
The striation of the cuticle as seen in surface view is shown in Text- 
fig. 21. It varies a little in the different forms, and it is significant that 
practically none occurs in the culture form. 
Text- fig. 21. Upper epidermal cells of S. binervosa (a-g), and o f .S', bellidifolia (h). a-h and 
K in transverse section, x 220; ai-ei, gi, hi, in surface view, showing striation of the cuticle, 
x 16S. A, Ai = Main bank plant; B, Bi — narrow-lenved lateral plant ; c, Cl = sand plant; D, 
D 1 — mud plant ; E, El — experimental plant; F = culture plant; G, gi = broad-leaved plant; it, 
hi = S. bellidifolia ; K — lower epidermis of a ‘sand’ plant of S. binervosa . c. = cuticle; i.c. — 
internal cuticle. 
Stomata occur on both surfaces of the leaf ; they show the constant 
character of being surrounded by three subsidiary cells (often four in 
S. bellidifolia ) (cf. Text-fig. 24, A and c). In all the forms examined they 
appear essentially similar in structure, and only differ in the fact that those 
of the Main bank plant are larger than in any other form, though those 
from the experimental area are nearly equal to them in size : the stomata 
of the mud form are the smallest, those of all the other plants are approxi- 
mately equal to those of the narrow-leaved plants. They usually occur on 
the level of the epidermal cells, though they may be very slightly raised 
above them. 
The number of stomata on the two sides of the leaf is approximately 
the same, but differences occur in the different forms, as is shown in 
