the Formation of the Vegetable Epidermis. 9 
expansion is circumscribed, however, by certain bounds or limits 
which it cannot pass. For, when it has become indurated with 
age, or when vegetation is too luxuriant, it refuses or is unable to 
expand further, and consequently bursts. But if it does not 
burst spontaneously, where it does not expand freely, it is then 
thought to check or retard the growth of the plant, by operating 
as a sort of tight roller or bandage; as may be exemplified in the 
case of the cherry-tree, the epidermis of which the gardener is 
often obliged to lay open by means of a longitudinal incision, in 
order to facilitate the growth of the parts inclosed. 
With regard to the disavowed analogy between the animal and 
vegetable epidermis, it is of no consequence to the above argu- 
ment whether it holds good or not. But there are several i impor- 
tant respects in which an analogy between the two cuticles is 
sufficiently striking. They are both capable of great expansion 
in the growth of the subject. They are both easily regenerated 
when destroyed, (with the exceptions above stated,) and seem- 
ingly in the same manner. They are both subject, in certain 
cases, to a constant decay and repair; and they both protect 
from injury the parts inclosed. Whence we feel ourselves en- 
titled to draw a conclusion directly the reverse of that of M. Mir- 
bel, namely, that the epidermis of the vegetable is not an acci- 
dental scurf formed on the surface of the parenchyma by means 
of the action of the air; but a distinct and individual organ formed 
by the agency of the vital principle, at the period of the genera- 
tion of the plant, and destined to the discharge of peculiar func- 
tions in the vegetable ceconomy, as well as exhibiting a close ana- 
logy to the epidermis of the animai. 
Stow Maries, Dec. 22, 1814. 
VOL. XII. c | Il. On 
