CHAP. II. 
STOMATES. 
55 
generally in most abundance on the under side. In succulent 
parts they are neither rare nor wholly wanting, as has been 
often asserted ; but are, on the contrary, as numerous as on 
many other parts. They may be generally seen upon the 
calyx; often on the corolla; and rarely, but sometimes, upon 
the filaments, anthers, and styles. In fruit, they have only 
been noticed upon such as are membranous, and not upon 
the coat of the seed ; not even upon those seeds which, as in 
Leontice thalictroides, grow exposed to air ; with the excep- 
tion of the genus Canna, in which Dr. Schleiden has found 
them, and to which he thinks them necessary in order to 
facilitate the passage of fluid through them to the interior of 
the seed. They exist upon the surface of cotyledons. 
Brown thinks that the uniformity of the stomates, in figure, 
position, and size, with respect to the meshes of the epidermis, is 
often such as to indicate the limits, and sometimes the affini- 
ties, of genera, and of their natural sections. He has shown, 
with his usual skill, that this is the case in Proteaceoe, in 
which statement he is supported by Schleiden, who seems to 
think that the structure of the stomatic opening will be mo- 
dified according to the physiological peculiarities of particular 
species, and that it will often indicate affinity. He mentions 
Cactaceae, Coniferae, Piperaceae, Agave, with some allied Lili- 
aceae, Commelinaceae, and Grasses, in illustration of this. 
(Wiegm. Arch. 1838. p. 59.) Brown also remarks, that on 
the microscopic character of the equal existence of stomates 
on both surfaces of the leaf depends that want of lustre which 
is so remarkable in the forests of New Holland. (Journal of 
the Royal Geogr. Society, i. *21.) 
The same botanist is of opinion, that the two glands, or 
rather bladders, of which a stomate is composed, are each 
analogous to the single bladders often found occupying the 
inner face of the meshes of the epidermis. (Plate HI. fig. 9.) 
(See the Memoir on the impregnation of Orchidece.) This idea is 
confirmed by the structure of Yucca (Plate HI. fig. 10.), in 
which the four oblong vesicles surrounding the stomate are 
evidently of the same nature as the free spheroidal vesicles 
(cytoblasts?) contained in the cells of the cuticle. 
The following table of the proportion of stomates on the 
E 4 
