PRINCIPLES OF SCIENTIFIC ARRANGEMENT. 137 
given, as, in the majority of modern works on natural 
history, use is frequently made of them. 
On carefully surveying any class or order of creatures, 
the mind speedily becomes impressed by observing cer¬ 
tain similitudes out of the direct line of continuous 
connection, and therefore remote from the strongest 
connecting links of positive relationship in the methodi¬ 
cal series. Induced thence to inspect them more closely, 
we presently ascertain that what we at first conceived 
might be an error in their collocation, arises from very 
strong resemblances in certain particular features, but 
which are less important than those which directly 
unite them, and may not be permitted to interrupt the 
order established. It is, however, equally evident that 
they indicate relations which may not be neglected. 
Thus, although the succession be direct in the evolu¬ 
tion of its primary characteristics, the prominent features 
which so present themselves establish the conviction 
of the existence of connections oblique to the straight 
line, but all embraced within the normal conditions 
which bind the group together. These are called re¬ 
lations of affinity. Pursuing them, it is sometimes 
observed that nature, as it were, returns upon itself, re¬ 
producing similar notes in another key. 
These indications have led philosophical naturalists to 
surmise that the true arrangement of natural objects is 
in groups, and not in a straight and continuous line. 
Several schemes have been suggested for the purpose 
of giving uniformity to these groups, making them 
equivalents by* associating together the same numbers 
of allied forms, which again return in a circular series 
upon themselves, and impinge upon other circles at the 
parallel points of their circumference by affinities less 
