INTKODUCTION TO CRYPTOGAMIC BOTANY. H] 



their decay forms a nidus for the growth of minute mosses ; soil 

 gradually accumulates from their decomposition, and that of 

 minute Phaenogams which succeed them, till the whole surface 

 is covered; the rock itself, if like granite, composed of parts 

 readily subject to deintegration, is by degrees coarsely pul- 

 verised, soil is formed, and the surface is ready to supply 

 the wants of man, and the various members of the animal 

 world which administer to his needs, or concur in the pre- 

 servation of the balance of the organised world, and of the 

 elements by which it is supported- Unimportant, then, as these 

 minute beiags may be at first sight, for many of them are 

 quite microscopic, even the more obscure perform an impor- 

 tant part in the economy of creation. Physiologically they 

 are of much interest, because they represent the component 



Fig 27. 

 a. Hcematococcus sanguineus, Ag., from an authentic specimen. 

 h. Bangia atropurpurea, Lyngb. 



c. Porphyra Boryana, Mont, from an authentic specimen. 

 All more or less magnified. 



parts of which the larger species are formed. It is impossible, 

 for LQstance, to trace the connexion between Navicula and 

 Schizonevna, Oloeocapsa and Seirosiphon, or by a threefold 

 bond between Hcematococcus, Bangia and Porphyra, without 

 acknowledging that this is the case, though we may not proceed 

 so far as Agardh in his notions, which extend to the point of 

 considering even Phffinogams as made up of Cryptogams. 

 The Cryptogams may indeed be representatives or analogues 

 of their organs, and the study of the one may be illustrated by 

 the other ; but we cannot go further consistently with sound 

 philosophy, and perhaps it may not have been the iatention of 

 Agardh, after all, however strong his language may be, to 



