CLASSIFICATION. 407 



same kind of natural classification which is best in biology 

 will apply also in mineralogy, in chemistry, or in astronomy. 

 The universal logical principles which underlie all classifi- 

 cations are of course the same in natural history as in the 

 sciences of brute matter, but the special logical resem- 

 blances which arise from the relation of parent and 

 offspring will not be found to prevail between different 

 kinds of crystals or mineral bodies. 



The genealogical view of the mutual relations of ani- 

 mals and plants leads us to discard all notions of any 

 regular progression of living forms, or any theory as to 

 their symmetrical relations. It was at one time a great 

 question whether the ultimate scheme of natural classifi- 

 cation would prove to be in a simple line, or a circle, or a 

 combination of circles. Macleay's once celebrated system 

 was a circular one, and each class-circle was composed of 

 five order-circles, each of which was composed again of 

 five tribe- circles, and so on, the subdivision being at each 

 step into five minor circles. Thus he held that in the 

 animal kingdom there were five sub-kingdoms the Ver- 

 tebrata, Annulosa, Radiata, Acrita, and Mollusca. Each 

 of these was again divided into five the Vertebrata con- 

 sisting of Mammalia, Eeptilia, Pisces, Amphibia, and 

 Aves. It is quite evident that in any such symmetrical 

 system the animals were made to suit themselves to the 

 classes instead of the classes being suited to the animals. 



We now perceive that the ultimate system will be an 

 almost infinitely extended genealogical tree, which wih 1 

 be capable of representation by lines on a plane surface 

 of sufficient extent. But there is not the least reason to 

 suppose that this tree will have a symmetrical form. 

 Some branches of it would be immensely developed com- 

 pared with others. In some cases a form may have pro- 



S Swainson, ' Treatise on the Geography and Classification of Animals, 

 'Cabinet Cyclopaedia/ p. 201. 



