GENERAL CLASSIFICATION OF ANIMALS. 15 



It appears from this account, that those parts of plants, 

 which perform the functions necessary to their nutrition and 

 growth, are strictly annual. So that all plants are either an- 

 nual, that is, wholly renewed every year, or at least have the 

 circulating vessels, and all the organs taking an active part 

 in their economy, annually renewed, viz. the alburnum, the 

 burk, the leaves, the flower, &/c. This circumstance affords 

 another very obvious general distinction between the vegeta- 

 ble and animal kingdoms; in the latter, nothing of the kind 

 is to be observed : there is in no case such a renewal of any 

 of the organs of which an animal is composed, any at least 

 of those concerned in performing important functions. It is 

 true that some of the subordinate parts, such as the hair, the 

 cuticle or scarf skin, the nails, teeth, feathers, &,c., are occa- 

 sionally and sometimes annually renewed in certain kinds of 

 animals. But there is no change in any of the principal or- 

 gans; the circulating system, the lungs, the stomach, &/c., 

 always remain the same.* 



The plan of this work does not admit a more full account 

 of the structure, functions, and classification of the vegetable 

 world ; and we proceed therefore to an examination of the 

 animal kingdom. 



CHAPTER III. 



OF THE STRUCTURE OF ANIMALS. 

 SECTION I. 



General Classification of Animals. 



IN order to treat clearly of the animal kingdom, it is neces- 

 sary to consider it according to some method of arrange- 

 ment, by which those animals that most resemble one another 

 are connected together for the convenience of description. 

 This arrangement is founded upon their form and structure. 



* It may here be observed, that in vegetables there is none of that absorption of the 

 different parts which takes place in animals. The matter of which they are com- 

 posed, being once deposited, is never taken up again; whilst in animals there is 

 a constant process going on, by which the old matter is taken away and new de- 

 posited, and the organs thus renewed. Perhaps this end is intended to oe answered 

 In vegetables by the annual renewing of their circulating system. 



