2 ZOOLOGY. 



it describes, and to horticulture, of which it is the guide ; to 

 recollect the animals to which we owe wool, silk, honey 

 which lend us that power which man so often requires, or 

 which, far from being useful to us, threaten our harvests with 

 destruction ; lastly, to consider the long catalogue of human 

 infirmities, and to reflect on the dangerous character of that 

 medicine which is not based on a scientific knowledge of the 

 human structure. But the utility of these sciences does not 

 stop here ; in an educational point of view, their study accus- 

 toms the mind to proceed from effect to cause, testing each 

 hypothesis by an appeal to facts. Finally, before all other 

 studies, that of natural history trains the mind to method, 

 that part of logic without which all investigation is laborious, 

 every exposition obscure. 



In claiming for natural history a place in every liberal 

 system of education, we do not mean that all young men 

 should become naturalists. So vast a study and the time 

 required for other studies forbid such an idea ; nor would the 

 acquisition of the details on which natural history is based be 

 of any service to the young mind : all that is necessary is 

 that sound, correct notions be placed before the student, and 

 acquired by him, respecting the great questions to solve which 

 is the object of natural history studies ; on the constitution 

 of the globe, for example, and the physical revolutions which 

 succeed each other on its surface ; on the nature of plants and 

 animals ; on the mode in which their functions are exercised ; 

 and on the principal modifications of their structure, accord- 

 ing to the kind of life for which they are destined. This 

 description of knowledge once acquired is seldom forgotten; 

 it forms a basis for the special studies of those who desire 

 to become naturalists ; and is sufficient for those whose pur- 

 suits do not lead to science. The University (of France) in 

 its programme sanctions this course of study, and enforces it ; 

 in this work we propose adopting it. 



2. Division of Natural JBodies into Three Kingdoms. 

 All natural bodies, whether spread over the surface of the 

 globe or collected in the interior of the earth, are of two 

 kinds mineral or unorganized, living or organized. These 

 last are subdivided into two groups vegetables and animals. 

 Hence has arisen the expression of the three great kingdoms 

 of nature the mineral, vegetable, and animal. In com- 

 mencing the study of these three kingdoms, it is necessary to 

 inquire, in the first place, on what basis these divisions rest, 



