82 THE EVOLUTION OF ANIMALS. 



the, higher animals gradually appear in successive periods 

 of the earth's history, are strong corroborations of the 

 theory. 



(2) It is less easy to state in a few words, how the facts of 

 geographical distribution, or the history of the diffusion of 

 animals from centres where the presumed ancestral forms 

 are or were most at home, favour the doctrine of descent. 



(3) The individual life-history of an animal— often strangely 

 circuitous or indirect — is interpretable as a modified recapitu- 

 lation of the probable history of the race. Every animal 

 starts as a Protozoon ; the morula and gastrula stages corres- 

 pond to the presumable beginnings of multicellular life. 

 The embryo mammal is at one stage somewhat like a young 

 fish, at another like a young reptile ; even in details, the 

 recapitulation, if such we may term it, is sometimes faithful. 



II. The Theory of Evolution. 



The doctrine of descent is now almost universally recog- 

 nised ; but there is much uncertainty in regard to the way 

 in which the evolution has been brought about. The fact 

 of evolution is admitted, while debate goes on with regard 

 to the factors. With the exception of Alfred Russel 

 Wallace and a few others, who postulate spiritual influxes 

 to explain the beginning of consciousness and the higher 

 human qualities, evolutionists are agreed in trying to explain 

 the evolution of plants and animals as a continuous natural 

 process, the end of which was implicit in the beginning. 

 In so doing they are following the method of analysis, — 

 trying to explain things in their lowest terms. As the. 

 biologist's lowest term is living matter, about which our 

 most certain knowledge is that it can in favourable circum- 

 stances think., there is no reason to call the evolutionist's 

 analysis " materialistic " — if anything opprobrious be meant 

 by that adjective. Nay more, even if he knew the chemical 

 and physical secret of living matter, — an advance not in 

 the least degree imminent at the present rate of progress, 

 he would know but a marvellous kind of ethereal motion, 

 of which again we have surest knowledge in our brains 

 when we think and feel. In short, the common denomin- 



