36 DESCRIPTIVE BOTANY. I'XHTI. 



both of the stem and leaves of phanerogamous plants 

 combined. In the lower tribes, however, there is sel- 

 dom any separation of parts into distinct organs, but 

 the functions of nutrition are carried on in an obscure 

 manner by the general mass. 



(_'.) Internal Organisation. 



The internal organisation of acotyledonous plants, is 

 not sufficiently uniform in the different orders, to allow 

 of their being characterised by any appellation derived 

 from their mode of development, as in the case of the 

 Exogenie and Endogense. But acotyledonous plants 

 may be separated into two groups : the one, termed 

 " Ductulosffi," characterised by the existence of a vas- 

 cular tissue, and by a mode of development much re- 

 sembling that of the Endogena; ; the other, termed 

 " Eductulosje," or " Cellulares," is entirely composed 

 of cellular tissue. De Candolle even considers the for- 

 mer group, in spite of their cryptogamic character, to 

 possess a monocotyledonous mode of development in 

 the germination of their sporules, and keeps them se- 

 parate from the others, as a distinct class. The latter 

 group may be strictly termed " Cellulares," from their 

 being composed of cellular tissue alone, and thus sepa- 

 rated from the " Vasculares," which will include the 

 rest of vegetation (as well cryptogamic as phanero- 

 gamic), possessing a vascular structure. The class Aco- 

 tyledones is, however, very readily recognisable by its 

 external appearance alone; and the general characters of 

 the several orders which it embraces ferns, mosses, 

 lichens, seaweeds, fungi, &c. are pretty familiarly 

 known as examples. 



(37-) Tabular J'inc. In the very slight sketch here 

 given of the primary groups under which all plants may 

 be arranged, we have not pretended to notice many 

 terms which different botanists have applied to them ; 

 but we shall now collect the substance of what we 

 have said in the form of a table, which may serve 

 to assist the memory of the reader in fixing any of 



