I.] ARE PLANTS CATAGENETIC ? 17 



have come ii-p through the ages, as Dipleurogenesis and 

 Centrogenesis. 



The two divergent directions of the lines or phyla of 

 evolution have often been the subject of comment, but 

 one of the sharpest contrasts between the two was made in 

 1884 by Cope, when he proposed that the vegetable king- 

 dom has undergone a degenerate or retrogressive evolu- 

 tion. "The plants in general," he then wrote, "in the 

 persons of their protist ancestors, soon left a free -swim- 

 ming life and became sessile. Their lives thus became 

 parasitic, more automatic, and in one sense degenerate." 

 The evolution of the plant creation is, therefore, held to 

 be a phenomenon of catagenesis or decadence. This, of 

 course, is merely a method of stating a comparison with 

 the evolution of the animal line or phylum, and is, 

 therefore, of the greatest service. For myself, however, 

 I dislike the terms retrogressive, catagenetic, and the like, 

 as applied to the plant creation, because they imply in- 

 trinsic or actual degeneracy. True retrogressive or de- 

 generate evolution is the result of loss of attributes. 

 Cope holds that the chief proof of degeneracy in the plant 

 world is the loss of a free-swimming habit; but it is 

 possible that the first life -plasma was stationary: at "any 

 rate, we do not know that it was motile. Degeneracy is 

 unequivocally seen in certain restricted groups where the 

 loss of character can be traced directly to adaptive 

 changes, as in the loss of limbs in the serpents. Re- 

 tarded evolution expresses the development of the plant 

 world better than the above terms, but even this is erro- 

 neous, because plant types exhibit quite as complete an 

 adaptation to an enormous variety of conditions as ani- 

 mals do, and there has been rapid progress towards spe- 

 cialization of structure. As a matter of fact, the vege- 



"J, SUR. 



