• the Formation of the Vegetable EpiJennis. 9 



expansion is circumscribed, however, by certain bounds or limits 

 which it cannot pass. For, when it has become indurated with 

 ago, or when vegetation is too luxuriant, it refuses or is unable to 

 expand further, and consequently bursts. But if it does not 

 burst s|)ontaneously, 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 ol)liged 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 consecjuence to the above argu- 

 ment whether it holds good or not. But there are several 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 oeconomy, as well as exhibiting a close ana- 

 logy to the epidermis of the animal. 



Stow Maries, Dec. 22, 1814. 

 VOL. XII. c III- On 



