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 

 vchich 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 



