94 EVOLUTION 



backbone^ Animals higher than 

 fishes r a. very high level of 



been reached by the plants. There were in 

 those days ferns and horsetails, club-mosses 

 and Pteridosperms, and many other plants of 

 high degree; what has happened since has 

 been specialization rather than great ad- 

 vance. It is true that the fern-like Pteir- 

 dosperms gave rise to the world-wide Meso- 

 zoic Cycadophytes, and, in still later times, 

 to the true Flowering Plants, but there was 

 no ffreat new organic invention ]\fc tlmt. of 

 the seed, for which the flower is but the pro- 

 tean birth-robe. JSince that, progress Jias 

 been in the intensive colonization of the 

 earth and in detailed adaptatigns. vegeta- 

 tive and floral, manifold and exquisite. 



In thinking of this, we must remember, in 

 the first place, that while the Devonian 

 period is inconceivably remote, there was an 

 equally inconceivable stretch of ages before 

 it, during which there must have been many 

 a great step among plants as well as among 

 animals. In tjie s^nnrl pla^e, foe ^Y** ^^ 



no siioTi vpry grpa.^ advance-:^- 



whereas animals | 

 have risen by stride after stride to higher and 

 higher levels of organization, is congruent 

 with the deep contrast between plants and 

 animals to which we have already referred. 



