Classification. 45 



ment of group subordinate to group, when due 

 regard is paid to degrees of anatomical resemblance 

 — this mere fact of itself tells so weightily in favour 

 of descent with progressive modification in different 

 lines, that even if it stood alone it would be entitled 

 to rank as one of our strongest pieces of evidence. 

 But, as we have seen, it does not stand alone. When 

 we look beyond this large and general fact of all the 

 innumerable forms of life being thus united in a 

 tree-like system by an unquestionable relationship of 

 some kind, to those smaller details in the science of 

 classification which have been found most useful as 

 guides for this kind of research, then we find that all 

 these details, or empirically discovered rules, are 

 exactly what we should have expected them to be, 

 supposing the real meaning of classification to have 

 been that of tracing lines of pedigree. 



In particular, we have seen that the most archaic 

 types are both simpler in their organization and more 

 generalized in their characters than are the more 

 recent types — a fact of which no explanation can be 

 given on the theory of special creation. But, upon the 

 theory of natural evolution, we can without difficulty 

 understand why the earlier forms should have been 

 the simpler forms, and also why they should have 

 been the most generalized- For it is out of the older 

 forms that the newer must have grown ; and, as they 

 multiplied, they must have become more and more 

 differentiated. 



Again, we have seen that there is no correlation 

 between the importance of any structure from a 

 classificatory point of view, and the importance of that, 

 structure to the organism which presents it. On the 



