222 THE FROG CHAP. 



other species, at some previous period of the earth's 

 history. 



Notice that on this theory the various species of frogs 

 are no more actually related to one another than is either 

 of them to a newt, or, for the matter of that, to man- 

 The individuals of any one species are truly related 

 since they all share a common descent, but there is no 

 more relationship between the individuals of any two 

 independently created species than between any two 

 independently manufactured chairs or tables. The words 

 affinity, relationship, &c., as applied to different species 

 are, on the theory of creation, purely metaphorical, and 

 mean nothing more than that a certain likeness or 

 community of structure exists ; just as we might say 

 that an easy chair was more nearly related to a kitchen 

 chair than either of them to a three-legged stool. 



We see, therefore, that on the hypothesis of creation, 

 the varying degrees of likeness and unlikeness between 

 the species receive no explanation, and that we get no 

 absolute criterion of classification : we may arrange our 

 organisms, as nearly as our knowledge allows, accord- 

 ing to their resemblances and differences, but the relative 

 importance of the characters relied on becomes a purely 

 subjective matter. 



According to the rival theory that of Descent or 

 Organic Evolution, with which the name of Darwin is 

 inseparably connected every species existing at the 

 present day is derived by a natural process of descent 

 from some other species which lived at a former period 

 of the world's history. If we could trace back from 

 generation to generation the individuals of any existing 

 species, we should, on this hypothesis, find their charac- 

 ters gradually change, until finally a period was reached 

 at which the differences were so considerable as to 



