CHAP. II. CUTICLE. 37 



water. Its usual character is that of a deUcate membrane, 

 but in some plants it is so hard as almost to resist the blade 

 of a knife, as in the pseudo-bulbs of certain Orchideous plants. 

 The most usual form of its reticulations is the hexagonal 

 (Plate III. fig. 11.): sometimes they are exceedingly uncer- 

 tain in figure; often prismatical ; and not unfrequently bounded 

 by sinuous lines, so irregular in their direction as to give the 

 meshes no determinate figure (fig. 5.). 



Botanists are not entirely agreed upon the exact nature of 

 the cuticle ; while the greater number incline to the opinion 

 that it is an external layer of cellular tissue in a dry and 

 compressed state; others, among whom are included both 

 Kieser and Amici, consider it a membrane of a peculiar na- 

 ture, transversed by veins, or vasa lymphatica. 



By the latter it is contended, that the sinuous direction of 

 the lines in many cuticles is incompatible with the idea of any 

 thing formed by the adhesion of cellular tissue ; that when it 

 is once removed, the subjacent tissue dies, and does not be- 

 come cuticle in its turn, and that it may often be torn up 

 readily without laceration. 



On the other hand, it is replied, that the reticulations of 

 the cuticle are mostly of some figure analogous to that of cel- 

 lular tissue, and that the sinuous meshes themselves are not so 

 different as to be incompatible with the idea of a membrane 

 formed of adhering bladders. We are accvxstomed to see so 

 much variety in the mere form of all parts of plants, tliat an 

 anomalous configuration in cellular tissue should not surprise 

 us. The lines, or supposed lymphatic vessels, are nothing 

 more than the united sides of the bladders, and are altogether 

 the same as are presented to the eye by any section of a mass 

 of cellular substance. It is certain that the cuticle cannot be 

 removed without lacerating the subjacent tissue, with however 

 much facility it may be sometimes separable : on the under 

 surface of the leaf of the Box, for instance, there has plainly 

 been some tearing of the tissue, before the cuticle acquired the 

 loose state in which it is finally found. If the subjacent epi- 

 dermis never becomes cuticle when the latter is removed, this 

 is no reason why the cuticle itself should not be composed of 

 cellular tissue; for it is an axiom in vegetable physiology? that 



D 3 



