132 ON SYSTEMATIC ZOOLOGY. 
of the subject, it results that there are many natural 
systems, or rather, that there are many attempts to ex- 
plain those complicated relations which belong to the 
natural series. We prefer, in this instance, a compre- 
hensive definition to a metaphysical one ; because, were 
we to adopt the latter, we should be compelled to con- 
sider the system of Mr. Mac Leay artificial, since many 
properties of natural groups have been since discovered, 
and several combinations detected, which were quite 
unknown when that system was given to the world. 
CHAP. 11: 
EXPOSITION, WITH REMARKS ON THE PRINCIPAL ARTIFICIAL 
SYSTEMS. — ARISTOTLE, WILLUGHBY, LINN/EUS, CUVIER. — 
PARTIAL SYSTEMS. — ILLIGER, VIEILLOT, TEMMINCK, IN OR- 
NITHOLOGY. — DE GEER, LATREILLE, CLAIRVILLE, AND LEACH y 
IN ENTOMOLOGY. — ON BINARY, OR DICHOTOMOUS, SYSTEMS. 
(184.) Tue advantages and the disadvantages of arti- 
ficial systems have been already touched upon (178.), 
and their use explained*; it remains, therefore, to give 
the reader a general idea of those systems which have 
been most celebrated, or most extensively adopted. As 
artificial systems are capable of endless diversity, so it 
would be impossible to enumerate, within reasonable 
limits, one half of those which have been already pub- 
lished ; setting aside others, which a very slight ac- 
quaintance with nature will enable every student to 
invent. One advantage has certainly attended that de- 
ference and respect with which—particularly in this 
country —the writings of the great Swede have always 
been treated ; for although an implicit deference to the 
* Preliminary_Discourse, c. iil. p. 188. 
