DIFFICULTIES OF A FIRST ARRANGEMENT. C03 



were no progression of developement. all animals 

 would be equally perfect— that is to say. have the 

 same complexity of structure. Here, then, lies his 

 difficulty. He perceives, perhaps, an evident affinity 

 between two groups, by species which seem to blend 

 them together, and to conduct him, by an almost 

 insensible gradation, from one to the other. He 

 therefore concludes this to be the natural series, and 

 he approximates them accordingly : presently, how- 

 ever, upon looking more attentively to his other 

 unsorted groups, he finds not only one, but several, 

 each of which, in some way or other, shows an ap- 

 proximation just as close to his first group, as that 

 does which he has previously made to follow it : and 

 he is as much at a loss how to dispose his groups 

 in natural succession, as he Mas how to place the 

 species which they contain. The same results also 

 attend his attempts at improving his arrangement of 

 groups: what is gained by shifting one so as to 

 follow another, is lost by dissevering it from that 

 with which it was previously united : until, with all his 

 assiduity and trials, he finds there is still a remnant 

 of " unknown things," which stand disconnected, as 

 it were, from the series he has formed : and which 

 cannot be made to fall into place by any contrivance 

 he can devise. 



(138.) Xow. the first question which arises in 

 such a state of things — a state which every naturalist 

 has repeatedly experienced. — is this: — What is 

 the series of nature ? Is it simple, or complex ? 

 and in what manner, or by what rules, am I to dis- 

 tinguish the different natures o'i all these compli- 

 cated relationships or resemblances, so as to deter- 



