18 



CHAPTER IV. 



OF THE CELLULAR INTEGUMENT. 



Immediately under the Cuticle we find a succulent 

 cellular substance, for the most part of a green colour, 

 at least in the leaves and branches, which is called bv 

 Du Hamel the Enveloppe cdlidaire, and by Mirbel 

 ^the Tissu herhac6. This is in general the seat of 

 colour, and in that respect analogous to the rete 

 mucosuniy or pulpy substance situated under the hu- 

 man cuticle, which is pale in the European, and black 

 in the Negro ; but we must carry the analogy no 

 further, for these two parts perform no functions in 

 -common. Du Hamel supposed this pulp to form the 

 cuticle; but this is improbable, as his experiments 

 •show, when that uicmbrane is removed, that the 

 Cellular Integument exfoliates, at least in trees, or is 

 thrown off in consequence of the injury it has sus- 

 tained, and a new cuticle, covering a new layer of the 

 same succulent matter, is formed under the old one. 

 Annual stems or branches have not the same power, 

 any more than leaves. 



But little attention has been paid to this organ till 

 lately, though it is very universal, even, as IMirbel ob- 

 serves, in Mosses and Ferns. The same writer remarks 

 that " leaves consist almost entirely of a plate of this 



