CHAP. II. 
CUTICLE. 
41 
croscopes ; and, 3. None of those arts which the microscopic 
observer knows so well how to employ, such as shifting, aug- 
menting, or decreasing the light, interposing moveable sha- 
dows between the mirror and the object, and the like, give 
the least indication of the presence of any membrane across 
the orifice of the stomate. I therefore conclude, that, in 
Crinum amabile, the stomates are formed by two elastic kid- 
ney-shaped bladders, lying over an opening in the middle of 
a contracted area of cuticle ; that these bladders, when ex- 
panded, meet, and press powerfully against each other, like 
two opposing springs ; thus causing the elevated ridge-like 
appearance visible in the axis of the stomate in the figure above 
reterred to ; and that, when contracted, they curve in an 
opposite direction, separating from each other, and ceasing 
to close up the aperture over which they lie. If it were pos- 
sible to be absolutely certain of the accuracy of this description, 
the structure of the stomate in Crinum amabile might be safely 
taken as the type of all others ; for, no doubt, they are all 
constructed upon a similar plan. Without actually asserting 
so much as this, it may be stated, that, of many hundreds of 
observations I have made upon this subject, I have not met 
with any thing tliat has led me to doubt the uniformity of 
their nature, or their general accordance with what is found 
in Crinum amabile, whatever that may be. Or at least, the 
only difference is this, that while the two bladders that form 
the edges of the aperture are distinctly separated at their ex- 
tremities in this plant, they are often confluent in others, as 
in Caladium esculentum. (Plate III. fig. 9.) All this appears 
fully confirmed by the curious observations of Mirbel, who 
found that in Marchantia the stomates are formed in the fol- 
lowing manner. The appearance on the upper surface of this 
plant of a depression with four or five bladders arranged in a 
circle, is a certain sign of the commencement of stomates. 
The bottom of this depression at a certain time is pierced by 
a large square hole, either by the destruction of a central 
bladder, or by the separation of the sides of four or five blad- 
ders at their angles nearest the centre of the depression. 
Several varieties are represented at Plate III.; besides 
which, stomates have been noticed by Link to be occasionally 
