SECT. I. ELEMENTARY ORGANS. 207 



trees, and fruits of rapid growth. Its expansion, 

 however, is circumscribed by certain bounds or 

 limits which it cannot pass ; for when vegetation is 

 too rapid, or when the parts have become indurated 

 with age, it refuses or is unable to expand further, 

 and consequently cracks, as in the bark of aged trees, 

 or in Melons of luxuriant growth ; the fissure being 

 for the most part perpendicular, though sometimes, 

 as in the Cherry-tree, horizontal. It is also much 

 more capable of expansion in some trees than others, 

 and remains longer smooth ; and where it does not 

 expand freely it is thought to retard in some degree 

 the developement of the interior parts, as in the case 

 of the Cherry-tree, the epidermis of which the gar- 

 dener is often obliged to lay open by a longitudinal 

 incision, in order to facilitate the growth of the 

 plant. 



With regard to the disavowed analogy between 

 the animal and vegetable epidermis, it is of no con- 

 sequence to the above argument whether it holds 

 good or not. But there are several respects in 

 which an analogy between the two cuticles is suffi* 

 ciently striking : they are both capable of great ex- 

 pansion in the growth of the subject ; they are both 

 easily regenerated when injured (with the exceptions 

 already stated), and seemingly 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 enclosed. 



