i6o 



Celts; or, Evolution. 



of what a species is, argues thus in behalf of evolu- 

 tion, against the Etudes Religieuses, etc., of last May: 

 " The drag-nets of scientific explorers discover such 

 a variety of zoological forms, that it is often im- 

 possible to apply to them the best systems of class- 

 ification so far adopted: types of transition abound: 

 between groups heretofore considered sharply sep- 

 arated, there are found intermediary groups; 

 and often one species differs from neighboring 

 species only by imperceptible shades." All this 

 reminds us, in the first place, of Dr. Romanes* strict- 

 ure on the " small and trivial differences of form " 

 which distinguish species; and the vicious circle 

 which he finds in such argumentation (No. 115). 

 And, secondly, supposing that they are, as most 

 of them are not, true species, then what is it 

 that is really meant by these " types of transition 

 abounding"? Only this: that, between species 

 known before, new ones are found, not known be- 

 fore. But, if so, the difficulties are multiplied, and 

 the effort of engineering to bridge over the new 

 chasms in all directions is only intensified. 



177. It is quite superfluous, at this date in the 

 history of science, to dwell upon the absence of 

 transitional types, such as might supply evolution 

 with a passage or line of march, from any one 

 species to any other. Fossil reptiles, the group of 

 whales, the tortoises and turtles, the frogs and 

 toads, these and many others, extant as well as ex- 

 tinct, came in without saying how they came. The 



