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 another 
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 
