62 VEGETABLE ORGANOGRAPHY. 



Section II. 

 0/ the Cuticle, properly so called. 



When the pellicle which covers the leaves is raised, 

 we see that it is a very fine membrane, marked with 

 spaces, varying in form in different plants, and often in 

 different parts of the same plant. 



Those who pretend that this pellicle is the external 

 wall of the common cellules of the leaf, rely upon the 

 following facts : — 



1st. It cannot be raised without tearing at the same 

 time the tissue of the cellules, and exposing a part of 

 the jmces. 



2d. The spaces on this pellicle are forms which bear 

 a more or less distinct analogy, either with those of the 

 cellules of the plant, or with those of the organ from 

 which the cuticle has been raised ; thus the cellules 

 of Grasses, and those of petioles, are in the form of an 

 elongated parallelogram, like the spaces of the cuticle 

 which covers them. 



Those, on the contrary, who maintain that the cuticle 

 is a peculiar membrane, marked with spaces by network, 

 which is not produced by the edges of the broken cel- 

 lules, remark — 



1st. That the denudation of the parenchyma of a leaf, 

 by the removal of the cuticle, is better explained by sup- 

 posing that the walls of the cellules adhere to the cuticle, 

 than by supposing that the two bodies are only one. 



2d. That if aU the spaces on the cuticle were always 

 of the same form as the subjacent cellules, one might 

 believe that they were owing to their rupture ; but it is 



