PEACTICAL ZOOLOGY. 



Chapter I. 

 THE PEOTOZOA. 



A PEOTOZOON is an animal wMch consists of only one cell, 

 the equivalent of a single cell of any of the tissues of a higher 

 animal. 



Protozoa are always of small size, and are usually micro- 

 scopic. 



I. AMCEBA. 



This protozoon is found at the bottoms of freshwater 

 pools, and in damp situations. Its iiidefinite and ever-chang- 

 ing form is characteristic, and has gained for it the name 

 'proteus animalcule.' There are several forms, the largest 

 of which are just visible to the naked eye, while others are 

 exceedingly minute. 



Place a drop of water containing AmcebcB on a sUde : 

 cover ; and sea/rch for the animal with a low power of the 

 microscope. When found, examine it with a high power. 



A. General appearance. 



The animM is an irregular mass of protoplasm running 

 out into irregular blunt processes or pseudopodia, the protru- 

 sion and retraction of which cause great changes in the form 

 of the cell. These pseudopodia may branch slightly. 



B 



