PREFACE TO THE FIRST EDITION. 
Havine devoted myself from my earliest youth to the stu- 
dy of comparative anatomy, that is to the laws of the or- 
ganization of animals and of the modifications this organiza- 
tion undergoes in the various species, and having, for nearly 
thirty years since, consecrated to that science every moment 
of which my duties allowed me to dispose, the constant aim of 
my labours has been to reduce it to general rules, and to pro- 
positions which may contain their most simple expression. 
My first essays soon made me perceive, that I could only 
attain this in proportion as the animals, whose structure I 
should have to elucidate, were arranged in conformity with 
that structure, so that in one single name of class, order, genus, 
&c. might be embraced all those species which, in their ex- 
ternal as well as internal conformation, have affinities either 
more general or particular. Now this is what the greater 
number of naturalists of that epoch had never attempted, and 
what but few of them could have effected, had they ever 
been willing to try, since a similar arrangement presupposes 
an extensive knowledge of the structures, of which it is partly 
the representation. 
It is true, that Daubenton and Camper had given facts, 
that Pallas had indicated views: but the ideas of these learned 
men had not yet exercised upon their contemporaries the in- 
fluence they merited. The only general catalogue of animals 
then in existence, and the only one we possess even now, the 
system of Linnus, had just been disfigured by an unfortunate 
editor, who did not even take the pains to examine the prin- 
