30 INTRODUCTION. 



and morbid phenomena, together with the means of 

 regulating the former and of counteracting the lat- 

 ter, may certainly be included in it. 



Natural history, however, in its more limited ac- 

 ceptation, may be considered as comprehending the 

 three great kingdoms of Nature, — the mineral, the 

 vegetable, and the animal, — the sciences treating of 

 which are named Mineralogy, Botany, and Zoology. 

 The first of these departments of knowledge compre- 

 hends, along with the consideration of simple minerals, 

 that of the masses produced by the aggregation of these 

 substances, and the changes effected upon them by 

 natural causes. Botany teaches us to distinguish and 

 arrange the subjects of the vegetable kingdom, points 

 out the forms and functions of their organs, investi- 

 gates their internal structure, traces them in their 

 distribution over the surface of the globe, and makes 

 known the various properties which render them 

 noxious or useful to us. Zoology treats of the va- 

 rious tribes of animals, marks their external forms, 

 compares their various organs, describes their ha- 

 bits, discloses the laws which regulate their distri- 

 bution over the continents and islands, arranges 

 them into families according to principles deduced 

 from their structure, and in general makes us ac- 

 quainted with all that belongs to their history. Al- 

 though it is unnecessary here to offer any extended 

 remarks on the cultivation of the vast field which is 

 thus opened up to us, yet, the science of animals 

 being intimately connected with the Series of Lives 

 which we propose to offer to the public, it may not 

 be improper to give a short account of its origin and 

 progress. 



In the History of Zoology, four eras are marked by 



