248 THE BIOCOSMOS PARTICULARIZED. 



phyte. So we may regard the Mosses (Bry- 

 ophytes) as the dual or separative stage of 

 the Plant-world, judged by the highest cri- 

 terion of its permanent existence, namely 

 Generation. It will be noticed that the Gener- 

 ative Process is adopted as the supreme 

 standard for ordering the ascending evolu- 

 tion of Plant-life ; since the introduction of 

 this method, Botany has taken a new depart- 

 ure. 



But now we must make a fresh transition, 

 namely to the third stage of the vegetal king- 

 dom. Here the striking outer manifestation 

 is the appearance of the corm as the Plant- 

 unit of form, instead of the thallus which has 

 prevailed in both the preceding divisions 

 (Thallophytes and Bryophytes). What is the 

 significance of the corm in this total evolution 

 of the Plant-world? It means that the fun- 

 damental vegetal form has now come to man- 

 ifestion in its triple members stem, root and 

 leaf and will stay through to the end. The 

 thallus had no such differentiation, though it 

 showed many pushes toward it, many prophe- 

 cies of it, many an impulse to reach it but 

 on the whole in vain. At last the corm comes 

 fortji quite fully formed in its three members, 

 though it too will evolve a good deal in the 

 future. Still it remains and thus gives a 

 chief criterion for the third and last grand 



