4-10 SYSTEM OF INSECTS. 
siderinfj a numerical arrangement of the Kingdoms of 
o o o 
Nature is the value of the component members of each 
group. It is by no means difficult to divide a Kmgdom, 
a Class, or an Order into two, or three, or five, or seven 
or more groups, according to any system we may be in- 
clined to favour ; but it is not so easy to do this so that 
the groups shall be of equal rank. Yet it seems re- 
quisite that in grouping our objects, as we descend to- 
wards the lowest term we should resolve each only into 
its primary elements, and of them form the next group; 
and so on till we come to species. When I say of equal 
rank, I do not mean an exact parity between the mem- 
bers into which a group is primarily resolvable, — because 
there will always be a degradation in descensu from the 
perfection of the type ; but merely that parity (to use a 
metaphor) that there is between children of the same 
mother, differing in their relative ages and approach to 
the perfection of their nature. Perhaps it may be ob- 
served with respect to the quinary system, that this con- 
dition is not complied with, since two of the groups taken 
per se appear really to form one group ; or to be much 
nearer to each other than to the remaining groups. But 
when it is taken into consideration that this great group, 
always resolvable into two, is the typical group, and that 
the two are really equal, or rather superior in value to 
the three others, the objection seems to vanish. 
With regard to all numerical systems we may observe, 
that since variation is certainly one of the most universal 
laws of nature, we may conclude that different numbers 
prevail in different departments, and that all the num- 
bers above stated as prevalent are often resolvable or 
reducible into each other. So that where Physiologists 
