SECTION I. PHYLUM PROTOZOA 



1. THE RHIZOPODA. 



The simplest members of the animal kingdom are, for 

 the most part, too small to be visible without the aid of the 

 microscope, or at least so small as to appear to the 

 unassisted eye as extremely minute specks, not distinguish- 

 able, unless in unusually active movement, from small 

 particles of non-living matter. Representatives of this 

 class of simple minute animals are to be found living under 

 a variety of different conditions ; they are abundant in 

 fresh water, running and stagnant, and they are equally 

 numerous in the sea, while they are also to be found living 

 in the fluids of cavities in the bodies of higher animals. 

 An example which will serve to illustrate some of the main 

 features of the class is the Proteus Animalcule or Amoeba. 

 Amoeba (Fig. i) is sometimes to be found by searching 

 with the aid of the microscope in water from stagnant 

 pools. To the unpractised beginner it is a difficult task to 

 discriminate between the microscopic particles of non-living 

 matter which form the main part of the sediment at the 

 bottom of such a pool debris of animal, vegetable, or 

 mineral nature and the object of which he is in search. 

 Numerous minute bodies will doubtless be seen which on 

 account of their active movements among the motionless 



