AN INTRODUCTION TO ZOOLOGY 



CHAPTER I 



INTRODUCTION 



i. DEFINITIONS 



THE science of Biology includes the sum of human knowledge 

 with regard to organisms. That branch of biology which deals 

 with animals is known as Zoology; that which relates to plants, 

 as Botany. Zoology may be defined as the body of facts and 

 doctrines derived from the scientific study of animals. Scien- 

 tific study demands accurate and painstaking observation carried 

 on with some definite end in view. The scientific study of 

 zoology attempts to gain an understanding of the structure and 

 activities of animals. It not only deals with the animals per se, 

 but also with their relations to both the organic and inorganic 

 worlds. 



The detailed investigation of animals has led to the establish- 

 ment of a number of subsidiary zoological sciences, several of 

 which are briefly outlined in the next few paragraphs. 



Systematic Zoology is concerned with the description of animal 

 species and their arrangement according to a logical plan of 

 classification. The exact meaning of the term species is a 

 live question at the present time, and systematic zoologists do 

 not agree as to what characteristics should be used in separating 

 one species from another. One investigator in this field gives 

 the following definition: "A species, as conceived by most 

 systematists at the present time, may be defined as a group of 

 interbreeding individuals which, while they may differ markedly 

 among themselves, yet resemble each other more closely than they 

 do those of any other group; the characters that distinguish the 



