308 VEGETABLE ORGANOGRAPHY. 



rather for simple metaphors than expressions of the 

 reality : thus, when the body of a cellular plant is 

 almost cylindrical and erect, the name of stem has been 

 given to it, and its ramifications have borne that of 

 branches ; when this same body is flat and membraneous 

 it has been named a leaf. This desire to refer the forms 

 of cellular plants to the terms used for vascular ones 

 has caused much confusion in the writings of Crypto- 

 gamic botanists. In order that the degree of homo- 

 geneity of structure, and the difference in the general 

 forms which are presented in cellular plants, may be 

 perceived at once, I shall rapidly give a description of 

 the nutritive organs in each family of this class. This 

 course appears to me the only one which can be followed 

 in the actual state of the science ; for we are so ill ac- 

 quainted v/ith each of these families, that it seems to me 

 impossible to make any general remarks, worthy of 

 confidence, upon the whole of the class. 



Section II. 



Of Mosses. 



The Mosses are those, of all cellular plants, which 

 have the greatest affinity to vascular ones, and they also 

 differ but very little, as to their appearance, from the 

 Lycopodiums, with which they have sometimes been 

 confounded. The great difference which separates them, 

 with regard to the organs of vegetation, is purely nega- 

 tive; it is that the trachege, the different orders of 

 vessels, and the stomata, are absent in Mosses ; the ex- 

 istence of tracheae and other vessels is not admitted by 



