PBACTICAL ZOOLOGY. 



CHAPTER I. 

 THE PKOTOZOA. 



A PEOTOZOON is an animal which 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 indefinite 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 Ammb& on a slide : 

 cover ; and search for the animal with a low power of the 

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



A. General appearance. 



The animal 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. 



