PRINCIPAL SYSTEMS OF ZOOLOGY 215 



SECTION IV 

 PERIOD OF CUVIER AND ANATOMICAL SYSTEMS 



The most important period in the history of Zoology begins, how- 

 ever, with the year 1812, when Cuvier laid before the Academy of 

 Sciences in Paris the results of his investigations upon the more in- 

 timate relations of certain classes of the animal kingdom to one an- 

 other,^*^ which had satisfied him that all animals are constructed upon 

 four different plans, or, as it were, cast in four different moulds. A 

 more suggestive view of the subject never was presented before to 

 the appreciation of investigators; and though it has by no means as 

 yet produced all the results which certainly are to flow from its fur- 

 ther consideration, it has already led to the most unquestionable im- 

 provements which classification in general has made since the days 

 of Aristotle, and, if I am not greatly mistaken, it is only in as far as 

 that fundamental principle has been adhered to that the changes 

 proposed in our systems by later writers have proved a real progress, 

 and not as many retrogxade steps. 



This great principle, introduced into our science by Cuvier, is ex- 

 pressed by him in these memorable words: "Si Ton considere le 

 regne animal d'apres les principes que nous venons de poser, en se 

 debarrassant des prejuges etablis sur les divisions anciennement ad- 

 mises, en n'ayant egard qu'a I'organisation et a la nature des animaux, 

 et non pas a leur grandeur, a leur utilite, au plus ou moins de con- 

 naissance que nous en avons, ni a toutes les autres circonstances ac- 

 cessoires, on trouvera qu'il existe quatre formes principales, quatre 

 plans generaux, si Ton peut s'exprimer ainsi, d'apres lesquels tous 

 les animaux semblent avoir ete modeles et dont les divisions ulteri- 

 eures, de quelque titre que les naturalistes les aient decorees, ne sont 

 que des modifications assez legeres fondees sur le developpement ou 

 I'addition de quelques parties, qui ne changent rien a I'essence du 

 plan." ^^ 



^° Annales du museum d'histoire naturelle, XIX (1812), 73. 



^ ["If one considers the animal kingdom according to the principles that we are 

 proposing, getting rid of the prejudices established by the divisions anciently admitted, 

 in having only to consider the organization and nature of animals, and not their size, 

 their use, whatever knowledge we have of them or all the other additional circum- 



