PRINCIPLES OF ZOOLOGY. 29 



sentially to our happiness, but which it would be quite inex- 

 cusable to neglect. This general view of Zoology, it is the 

 purpose of this work to afford. 



11. A sketch of this nature should render prominent the 

 more general features of animal life, and delineate the ar- 

 rangement of the species according to their most natural 

 relations and their .rank in the scale of being ; thus giving 

 a panorama, as it were, of the entire Animal Kingdom. 

 To accomplish this, we are at once involved in the question, 

 What is it that gives an animal precedence in rank ? 



12. In one sense, all animals are equally perfect. Each 

 species has its definite sphere of action, whether more or 

 less extended, its own peculiar office in the economy of 

 nature ; and a complete adaptation to fulfil all the purposes 

 of its creation, beyond the possibility of improvement. In 

 this sense, every animal is perfect. But there is a wide 

 difference among them, in respect to their organization. In 

 some it is very simple, and very limited in its operation ; in 

 others, extremely complicated, and capable of exercising a 

 great variety of functions. 



13. In this physiological point of view, an animal may be 

 said to be more perfect in proportion as its relations with the 

 external world are more varied ; in other words, the more 

 numerous its functions are. Thus, an animal, like a quad- 

 ruped, or a .bird, which has the five senses fully developed, 

 and which has, moreover, the faculty of readily trans- 

 porting itself from place to place, is more perfect than a 

 snail, whose senses are very obtuse, and whose motion is 

 very sluggish. 



14. In like manner, each of the organs, when separately 

 considered, is found to have every degree of complication, 

 and, consequently, every degree of nicety in the perform- 

 ance of its function. Thus, the eye-spots of the star-fis-h 

 and jelly-fish are probably endowed with merely the fac- 



