THE EVIDENCE FROM DEGENERATION. 



343 



as advance. Physiological history can readily be proved to tend in 

 many cases towards backsliding, instead of reaching forwards and 

 upwards to higher levels. This latter tendency, beginning now to 

 be better recognised in biology than of late years, can readily be 

 shown to exercise no unimportant influence on the fortunes of 

 animals and plants. In truth, life at large must now be regarded as 

 existing between two great tendencies the one progressive and 

 advancing, the other retrogressive and degenerating. Such a view of 

 matters may serve to explain many things in living histories which 

 have hitherto been regarded as somewhat occult and difficult of 

 solution j whilst we may likewise discover that the coexistence of 

 progress and retrogression is a fact perfectly compatible with the 

 lucid opinions and teachings concerning the origin of living things 

 which we owe to the genius of Darwin and his disciples. 



A fundamental axiom of modern biology declares that in the 

 development of a 

 living being we may 

 discern a panoramic 

 unfolding, more or 

 less complete, of its 

 descent. "Develop- 

 ment repeats de- 

 scent" is an aphor- 

 ism which, as we 

 have seen, cultured 

 biology has every- 

 where writ large 

 over its portals. Re- 

 jecting this view of g 

 development and its' 

 teachings, the phases'" 

 through which ani- 

 mals and plants pass 

 in the course of their 

 progress from the 

 germ to the adult 

 stage present them- 

 selves to view as 

 simply meaningless 

 facts and useless freaks and vagaries of nature. Accepting the idea 

 favoured, one may add, by every circumstance of life-sciencemuch 

 that was before wholly inexplicable becomes plain and readily under- 

 stood. And the view that a living being's development is really a 

 quick and often abbreviated summary of its evolution and descent, both 

 receives support from and gives countenance to the general conclusion 



FIG. 241. DEVELOPMENT OF FROG. 



