THE CONVERGENCE OF IHE EVIDE]SCES. 471 



there could be no rational hesitation which of the two views 

 should be entertained. 



§ 172. Further means of judging, however, we found to 

 be afforded by bringing the two hj^otheses face to face with 

 the general truths established by naturalists. These induct- 

 ive evidences w^ere dealt with in four chapters. 



** The Arguments from Classification ^^ were these. Organ- 

 isms faU into groups ■\;\ithin groups ; and this is the arrange- 

 ment which we see results from evolution, where it is kno^^n 

 to take place. Of these groups within groups, the great or 

 primary ones are the most unlike, the sub-groups are less 

 unlike, the sub-sub-groups still less unlike, and so on ; and 

 this, too, is a characteristic of groups demonstrably produced 

 by evolution. Moreover, indefiniteness of equivalence among 

 the groups^ is common to those which we know have been 

 evolved, and those here supposed to have been evolved. And 

 then there is the further significant fact, that divergent 

 groups are allied through their lowest rather than their 

 highest members — a truth which the hj^o thesis of evolution 

 implies. 



Of ^^the Arguments from Embryology,^' the first and most 

 striking is, that when the developments of embryos are traced 

 from their common starting point, and their divergences and 

 re-divergences sjnnbolized by a genealogical tree, there is 

 manifest a general parallelism between the arrangement of 

 its primary, secondary, and tertiary branches, and the 

 arrangement of the divisions and sub- divisions of our classi- 

 fications — a general parallelism to be anticipated as a result 

 of evolution. Xor do those minor deviations from this 

 general parallelism, which at first sight look like difficulties, 

 fail, on closer observation, to become additional supports ; 

 since those traits of a common ancestry which embryology 

 reveals, are, if modifications have resulted from changed con- 

 ditions, liable to be distorted or disguised in quite different 

 ways and degrees in different liues of iescendants 



