PRACTICAL ZOOLOGY 25 



The process of respiration cannot be followed in this 

 organism, there being no definite organs analogous to 

 the gills and lungs of higher forms devoted to this 

 function ; but the interchange of oxygen and carbon 

 dioxide, which is the essential part of the process, is 

 believed to take place through the superficial part of 

 the body. 



The nervous properties of the animal are well shown 

 when it comes in contact with a foreign body, evidence 

 for the possession of the sense of touch being easily 

 obtained while the movements are being watched. 



The contractions of the body substance show that it 

 is muscular. 



In exceptional circumstances, an amoeba in the 

 process of division, or fission, may be found, the body 

 separating into two parts connected at first by a thread 

 of protoplasm .which eventually breaks, two distinct 

 organisms thus being formed. This process may be 

 more easily studied, however, in Paramecium^ the " slip- 

 per animalcule." Preceding the division of the single 

 cell composing the body, there is a division of its 

 nucleus. Some of the "shelled" forms, like Arcella 

 and Difflugia, may be used for comparison. 



Euglena 



Material. Some of the green scum which forms on 

 the inside of aquaria is likely to yield abundant speci- 

 mens. If not, they may usually be raised by allowing 

 some pieces of green-coated bark, or a portion of a 

 flowerpot covered with the green film which forms on 

 the sides of damp pots, to stand covered with water in 

 a dish in a sunny place for several days. Scrape off 

 some of the green film in the bottom of the dish, and 

 examine according to the directions given for amoeba. 

 The animal may be recognized by its green color, 



