LEAPLIKE ORGANS IN CBYPTOGAMIA. 149 



addition to their other functions, the -leaves of Ferns very com- 

 monly bear the fructification upon their under surface ; and hence 

 the name frond has been given to them, for the purpose of dis- 

 tinguishing them from the leaves of the Phanerogamia, in which 

 they never bear a part in the production of seed. In some of 

 the Ferns, as the Osmunda regalis, or Flowering-Fern (as it has 

 been incorrectly called), a handsome and well-known species 

 common in some parts of England, the fructification is only borne 

 on the edges of particular leaves, which are much less expanded 

 than the rest; these are, therefore, called fertile fronds ; whilst 

 the other leaves, which here altogether resemble those of Flow- 

 ering-plants in function, are called sterile fronds. In MOSSES, 

 we observe a large number of minute and delicate leaflets, 

 having no concern in the fructification, which is entirely dis- 

 tinct ; but they have not those peculiarities of structure which 

 distinguish the leaves of higher plants, being destitute of a 

 woody skeleton and of stomata; and they seem to have a 

 greater mixture of function, since they not unfrequently send 

 out root-fibres from their under surfaces, for the purpose of 

 absorption. 



223. We observe in the lower and simpler tribes, as has been 

 heretofore shown, a much greater blending of different functions, 

 than in the higher ; which last possess a special organ for each, 

 and in which they are consequently performed in a more energetic 

 manner. Thus, when we descend below the Mosses, we find no 

 distinct leaves; they become, as it were, blended with the 

 general surface ; and all their functions are performed (as in the 

 Cactus tribe) by this. Such, it will be remembered, is the case 

 in the Liverworts (. 32) ; and also in the LICHENS and ALGM, 

 in many of which, however, we notice a flat expanded surface, 

 by which the functions of leaves may be in some degree per- 

 formed. This expanded surface is often of great extent in the 

 Algae, and possesses a very leaf-like aspect ; but, as already 

 stated, it does not perform the functions of leaves alone, but is 

 everywhere equally adapted for absorbing the fluid that consti- 

 tutes its nourishment, and in many instances contains the fructi- 

 fication also imbedded in its substance (. 41). 



