4 ELEMENTARY ZOOLOGY. 



and any study of man whether of his physical, mental, 

 social, or moral qualities is a part of Zoology, although 

 we do not usually include such studies in our text-books 

 of Zoology. 



For the sake of convenience, names have been given 

 to the various departments or divisions of the study of 

 animals. If we are chiefly interested about the form 

 and structure of animals we call the work morphology or 

 anatomy; if about the activities and powers of the various 

 parts in relation to each other, we call it physiology; if 

 about the way in which "the habits or organs of the ani- 

 mal help to adjust it to its external conditions of life 

 and make life satisfactory, we call it ecology. 



Again, we may study animals with reference to their 

 distribution on the face of the earth. We may determine 

 whether they are found on one continent or another; 

 in this or that latitude; whether they live on land or in 

 water, fresh or salt. Evidently many natural forces 

 and conditions enter into such questions as these. (See 

 Chapter XXVIII.) 



It is possible to study the life history of an individual 

 animal from its earliest stage to its mature condition, 

 noting all changes in structure and powers and modes of 

 life. This is embryology, and is one of the most interest- 

 ing and instructive fields of Zoology. 



If we study animals in respect to their similarities and 

 unlikenesses and classify them into families or groups 

 of more or less similar forms, on the basis of all we know 

 concerning them, we have what is called systematic 

 Zoology. By means of this kind of study the animals 

 that have been studied have been named and described 

 and placed in the scheme of classification, as near as 

 possible to the other forms that they most resemble. 



