22 FOOT-NOTES TO EVOLUTION. 



ones. The evolution of the earth and its life has rarely 



been subject to great leaps and catastrophes. Yet 



epoch-making events have taken place 



Epoch making ^^ ^^le earth. Such changes in life, as 



events. ^, .... r i ~ r • r 



the acquisition of lungs, of wings, of 



speech, are marked by the increased rapidity of the pro- 

 cesses of evolution. 



Professor Bergen says: "Until an evolutionary rise 

 of species had been assigned as an explanation of the 

 succession of higher and higher animals and plants 

 throughout the geological ages, what adequate reason 

 for this progress of life could be given ? Strike out 

 from our present conception of the organic world, class 

 after class, all notion of actual relationship by descent, 

 and what have we left but a mighty host of extinct 

 creatures whose rise, progress, and disappearance are 

 far more unaccountable than that of the genii in the 

 Arabian Nights ? " 



But not all change has been progress. The idea of 

 some of the earlier evolutionists that the advance of 

 life has been the simple result of an in- 

 Change not ^^^^ <, uniform tendency toward pro- 



progress. . ,, , ■ ■^ T> 



gression can not be maintained. I'or 

 progress, while general, is by no means uniform or uni- 

 versal. Progress ceases when its direct cause ceases. 

 In every group there are some members characterized 

 by degeneration and loss of specialization. This is in- 

 volved in the theory of " natural selection." If prog- 

 ress comes through competition, lack of competition 

 would imply retrogression. When animals or plants are 

 withdrawn from the stress of life to some protected con- 

 dition, the character of the type is lowered. There is 

 less need for specialization when the range of wants is 

 narrowed. Hence it is that all parasitic animals or 

 plants — lice, leeches, dodders, mistletoe, Indian pipe — are 



