8 ON THE LAW WHICH HAS REGULATED 



the lines of affinity, as intricate as the twigs of a 

 gnarled oak or the vascular system of the human 

 body. 'Again, if we consider that we have only frag- 

 ments of this vast system, the stem and main branches 

 being represented by extinct species of which we have 

 no knowledge, while a vast mass of limbs and boughs 

 and minute twigs and scattered leaves is what we 

 have to place in order, and determine the true posi- 

 tion each originally occupied with regard to the others, 

 the whole difficulty of the true Natural System of 

 classification becomes apparent to us. 



We shall thus find ourselves obliged to r.eject 

 all those systems of classification which arrange 

 species or groups in circles, as well as those 

 which fix a definite number for the divisions of 

 each group. The latter class have been very gener- 

 ally rejected by naturalists, as contrary to nature, 

 notwithstanding the ability with which they have 

 been advocated ; but the circular system of affini- 

 ties seems to have obtained a deeper hold, many 

 eminent naturalists having to some extent adopted 

 it. We have, however, never been able to find a 

 case in which the circle has been closed by a 

 direct and close affinity. In most cases a palpable 

 analogy has been substituted, in others the affinity 

 is very obscure or altogether doubtful. The com- 

 plicated branching of the lines of affinities in 

 extensive groups must also afford great facilities 

 for giving a show of probability to any such 

 purely artificial arrangements. Their death - blow 



