CHAP. II. 
CUTICLE. 
39 
no means uncommon ; he even thinks it is present in sub- 
mersed leaves, and imagines that it overHes the stigma in 
some plants. I, however, find nothing very definite in 
regard to this, except that the pellicle often exists, and that it 
does, not cover the stomates, 
2. Of Stomates. 
In most plants the cuticle has certain openings of a very 
peculiar character, which appear connected with respiration, 
and which are called Stomates^ or Stomata. (Plate jxissim.) 
Stomates [Pores of the epidermis ; Pores corticaux, allonges^ 
evaporatoires, or (/rands poj'es ; Glands corticales^ miliaires, or 
epidermoidales ; Glandulce cutanece ; Oeffnungen ; Stomatia ;) 
are passages through the cuticle, having the appearance of 
an oval space, in the centre of which is a slit that opens or 
closes according to circumstances, and lies over a cavity in the 
subjacent tissue. 
There is, perhaps, nothing in the structure of plants upon 
which it is more difficult to form any satisfactory opinion 
than these stomates. Malpighi and Grew, the latter of whom 
seems first to have figured them (t. 48., fig. 4.), call them 
openings or apertures, but had* no exact idea of their struc- 
ture. Mirbel also, for a long time, considered them pores, and 
figured them as such ; admitting, however, that he suspected 
the openings to be an optical deception. De Candolle enter- 
tains no doubt of their being passages through the cuticle. 
He says their edge has the appearance of a kind of oval 
sphincter, capable of opening and shutting. The membrane 
that surrounds this sphincter is always continuous with that 
which constitutes the network of the cuticle : under the latter, 
and in the interval between the pore and the edge of the 
sphincter, are often found molecules of adhesive green matter 
{Organogr. i. 80.) ; and recently Adolphe Brongniart, in his 
beautiful figures of the anatomy of leaves, would seem to have 
settled the question beyond all dispute. (Annales des Sciences., 
vol. xxi.) Nevertheless there are anatomists of high reputation 
who entertain a directly opposite opinion ; denying the ex- 
istence of passages, and considering the stomates rather in 
n 4 
