OF NATURAL AND ARTIFICIAL SYSTEMS. 189 



able systems and methods which have been, and are 

 still, in use. One writer attaches a primary im- 

 portance to particular characters, which anothei 

 undervalues ; a third rejects both these, and founds 

 his system upon certain points of structure on which 

 his predecessors have placed no value ; a fourth, 

 disregarding all outward organisation, builds his 

 method upon internal anatomy. The first question, 

 therefore, which a student naturally asks, is this ; — 

 Where, amid these opposing systems, am I to 

 choose ? None of them rest on, or appeal to, any 

 general laws of arrangement, applicable to other 

 departments of nature besides that upon which 

 they treat. The classification of each author rests 

 solely upon his own opinion how certain facts are to 

 be arranged. Individual dogma seems to be the 

 only basis. Mr. A. considers insects should be 

 classed according to their wings ; Mr. B. contends 

 that they are best arranged by regarding their feet. 

 What, then, we must first enquire, are those con- 

 siderations which should guide us in a choice of 

 system ? 



(130.) Now, systems may be of two kinds, arti- 

 ficial and natural. By artificial systems is to be 

 understood any mode of arranging objects according 

 to the absence or presence of certain given charac- 

 ters, without regard to such others as they may 

 possess ; or, if we arranged them simply according 

 to their modes of life, without any reference to their 

 particular structure. Thus, if all molluscous animals 

 were arranged into those which had shells, and 

 those which had none ; and these former, again, into 

 univalves, bivalves, and multivalves; this would 



