ZOOLOGY 



of the cortical layer has also rendered locomotion by pseudo- 

 podia rare, and those Corticata which move about actively 

 do so as a rule by means of rows of cHia or by a single or 

 paired flageUum. 



Class I. Flagellata. 



The bodies of the members of this class are usually very 

 minute, and always contain a nucleus ; they are moved by the 

 lashing of one, sometimes by two or three flageUa. A movith 



Fio. 17. — I. Typical form of Euglena viridis, Ebih., after Sav. Kent. 



1. Contractile vacuole. 3. Gullet and origin of flageUum. 



2. Pigment spot. 4. Nucleus. 



II. III. IV. V. Pour views of Euglena viridis, showing the change of shape 

 consequent upon the euglenoid movement. 



may be present, but in those forms which live in nutritive 

 fluids the nourishment is usually imbibed by the whole surface 

 of the body. One or more contractile vacuoles occur, and 

 sometimes a pigment spot is situated at one end of the body. 

 Conjugation sometimes occurs, and is followed by the breaking 

 up of the body into spores, reproduction also takes place by 



