NATURE OF THE EVIDENCE 17 



from the higher Cryptogams; it is, however, 

 obvious that they were not descended from any 

 Cryptogams now living, nor, in all probability, 

 from any plants at all closely resembling them; 

 Ferns and Club-mosses have changed in the 

 course of ages as well as Conifers, though perhaps 

 not to the same extent. The utmost we can get 

 out of the comparison of living plants is the con- 

 clusion that the ancestors of one group (which 

 we usually call the higher) were more or less like 

 the members of another group (which we usually 

 call the lower). 



The idea of "higher" and "lower" is, however, 

 very likely to lead us wrong. Many people 

 suppose that Evolution means progress from the 

 lower to the higher, from the simple to the com- 

 plex, and are therefore apt to assume that a 

 simple group of organisms is likely to represent 

 the ancestry of a more complex, related group; 

 very often, however, the reverse is the truth. 



For example, a beginner might very natur- 

 ally suppose that the Duckweeds, Flowering 

 Plants as simple as Liverworts, with no regular 

 distinction between stem and leaf, represent a 

 primitive, ancestral stage in the evolution of the 

 higher families of Flowering Plants; all botanists, 

 however, are agreed that the Duckweeds are 

 really degenerate water-forms, degraded from 

 higher plants in consequence of their mode of 



