390 THE INDUCTIONS OF BIOLOGY. 



It is, indeed, a wholly gratuitous assumption that organ- 

 isms admit of being placed in groups of equivalent values; 

 and that these may be united into larger groups which are 

 also of equivalent values; and so on. There is no a priori 

 reason for expecting this; and there is no a posteriori evi- 

 dence implying it, save that which begs the question — that 

 which asserts one distinction to be generic and another to be 

 ordinal, because it is assumed that such distinctions must be 

 either generic or ordinal. The endeavour to thrust plants 

 and animals into these definite partitions is of the same 

 nature as the endeavour to thrust them into linear series. 

 Not that it does violence to the facts in anything like the 

 same degree; but still, it does violence to the facts. Doubt- 

 less the making of divisions and sub-divisions, is extremely 

 useful ; or rather, it is necessary. Doubtless, too, in reducing 

 the facts to something like order they must be partially dis- 

 torted. So long as the distorted form is not mistaken for the 

 actual form, no harm results. But it is needful for us to 

 remember that while our successively subordinate groups 

 have a certain general correspondence with the realities, they 

 tacitly ascribe to the realities a regularity which does not 

 exist. 



§ 102. A general truth of much significance is exhibited 

 in these classifications. On observing the natures of the 

 attributes which are common to the members of any group 

 of the first, second, third, or fourth rank, we see that groups 

 of the widest generality are based on characters of the greatest 

 importance, physiologically considered; and that the charac- 

 ters of the successively-subordinate groups, are characters of 

 successively-subordinate importance. The structural pecu- 

 liarity in which all members of one sub-kingdom differ from 

 all members of another sub-kingdom, is a peculiarity that 

 affects the vital actions more profoundly than does the struc- 

 tural peculiarity which distinguishes all members of one 

 class from all members of another class. Let us look at a 

 few cases. 



