ELEMENTARY ZOOLOGY 



CHAPTER I. 

 THE UNICELLULAR ORGANISMS. 



The AmceBa {Ammba, various species). 



Water from any stagnant pool, particularly if a drop be taken 

 from the surface of the mud at the bottom, will be frequently 

 found to contain examples of an organism known as Amoeba. 

 This term is used rather loosely for a number of creatures — 

 fresh-water, marine, terrestrial (in damp earth) — which agree 

 in being composed of a speck of seemingly jelly-like substance, 

 and in moving by a flowing motion, accompanied by the 

 thrusting out of processes of the irregularly shaped body. 

 Some little experience of these organisms will soon show that 

 there are many kinds of amoebae, which have been classed by 

 naturalists in different species and even genera;^ some, for 

 instance, are larger, much larger, than others. The form of 

 the thrust-out processes of the body — the pseudopodia, as they 

 are termed — differs from species to species; the more or 

 less granular appearance of the body is another character 

 which varies in the different kinds ; and there are other points 

 of difference. In all these organisms, however, the body has 

 no fixed form ; it is simply an irregular mass of living matter ; 

 hence the name of " Proteus animalcule " was applied to it by 

 some of the earlier observers. When an amoeba, preferably 

 one of the larger species, is examined, it is seen to consist of 



' The terms "genera" and "species" are explained later (see p 173). 



B 



