MOBPHOLOG T. 5 



through the orderly operations of physical and biological 

 laws, under the guidance of an Infinite Intelligence— a 

 Creator whose modes of working are revealed to us in what 

 we call the laws or processes of nature. 

 Zoology is subdivided thus : 



I Morphology or gross Anatomy, and minute 

 I Anatomy (Histology). 



1 Physiology and Psychology. 

 Zoology. < Reproduction and Embryology. 



J Systematic Zoology or Classification. 

 / Palaeontology. 

 I Zoogeography. 



Morphology. — In order to properly understand Zoology, 

 one should first study Morphology — i.e., the general struc-. 

 ture of animals. The student should first thoroughly ac- 

 quaint himself with the anatomy of a vertebrate animal, 

 such as a frog, as compared with that of a toad or salaman- 

 der. The examination and comparison of the organs of 

 animals belonging to distinct groups, is called Comparative 

 Anatomy. The study of Morphology also includes the rela- 

 tion of the different organs to one another, and of all to the 

 walls of the body. Finally, we need also to study the com- 

 position of the tissues of the different organs ; each kind of 

 tissue being formed of different kinds of elements or cells. 

 This department of Comparative Anatomy is called Histol- 

 ogy (Greek, iGrdi, web or tissue ; Ad;/o?, discourse). It 

 treats of the cell, and the combination of cells into germ- 

 layers, tissues, and organs. 



The Cell. — The primary elements of the bodies of animals 

 are called cells. They are microscopic portions of proto- 

 plasm either with or without a wall. Protoplasm largely 

 consists of protein, which is a complex compound of car- 

 bon, hydrogen, oxygen, and nitrogen, united with a large 

 pi'oportion of water. Cells are originally more or less 

 spherical sacs, and the protoplasm forming the cell-mass is 

 the dynamic part of the cell. The protojolasm of animal as 

 well as vegetable cells, the protoplasm of eggs and of tlie 

 cells forming the different tissues of the animal body, as 



