THE FIELD OF ZOOLOGY 5 



7. Definition of Zoology. — A study of animals from every aspect 

 constitutes the science of zoology. This broad field is capable of being 

 divided into many of less extent depending on the various aspects from 

 which animals may be viewed, whether considered in whole or in part, 

 as to structure or function, in relation to the inorganic environment or 

 to other animals and the plants about them, or from the standpoint of 

 the principles and laws which underlie and determine the phenomena 

 exhibited by animal hfe. 



8. Divisions of the Subject. — Zoology may be divided, in accordance 

 with the manner in which animals are studied, into two great sub- 

 sciences; these are morphology, which deals with animals as to form 

 and structure, and physiology, which deals ^vith them as to their functions. 



Under the head of morphology are included anatomy, which is con- 

 cerned with structure as made out by dissection; histology, which treats 

 of structure as determined by the microscope; taxonomy, which is the 

 study of the laws and principles of classification and which is based upon 

 structure; geographical distribution, or zoogeography, the study of the 

 geographic distribution of animals; and paleozoology , which deals with 

 the fossil remains of animals. The reason for the placing of zoogeography 

 under morphology is that in this field animals are treated as species or 

 groups, a morphological basis. 



Physiology includes physiology in the narrow sense, which deals with 

 the functions of the different parts of which the body is composed; 

 ecology, which deals with the functional relations of animals to their 

 environment ; psychology, which is the study of the mental life of animals ; 

 and sociology, which is the study of animal societies. 



Three other fields belong to both morphology and physiology — 

 embryology, which deals with the early development of ammah; pathology, 

 which relates to the diseases that affect them; and parasitology, which 

 is concerned with animals that live at the expense of their fellows. No 

 effort has been made up to the present time, however, to separate the 

 structural and the functional aspects in any of these three fields. 



Not only may zoology be divided into the two broad subsciences first 

 named and their various divisions, based upon the manner of approach 

 and method of investigation, but it also may be separated into many 

 restricted sciences, each of which deals with a particular group. Among 

 these are protozoology, which deals with the lowest, one-celled animals; 

 helminthology, which is concerned wdth the worms; entomology, which is 

 the study of insects; conchology, the study of mollusks; ichthyology, the 

 study of fishes; herpetology, the study of reptiles and amphibians; or7ii- 

 thology, the study of birds; and mammalogy, the study of mammals. 

 Many other sciences, which concern less extensive groups and are less 

 familiar, might be added to this list, but only one need be spoken of and 

 that is anthropology, which is the study of man as to his physical nature. 



