222 THE FROG CHAP. 



the progenitors of all the 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 relation- 

 ship between the individuals of any two independently 

 created species than between any two independently manu- 

 factured 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, according to their re- 

 semblances 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 characters gradually change, until 



