200 



PROTOZOA. 



Class II. Flagellata (Mastigophora). 



In many Khizopoda, as described in the foregoing pages, the 

 pseudopodia disappear from time to time and are replaced by one 

 or two flagella ; others have, besides pseudopodia, permanent 

 flagella for locomotion and taking of food. Such flagellate spores 

 and flagellate Ehizopods form the transition to the Mastigophora, 

 which are permanently flagellate, the flagella serving as organs of 

 locomotion and feeding. There are three orders which must be 

 described separately. 



Order I. Autoflagellata. 



All autoflagellates at first sight are closely similar, a usually 

 oval body with a vesicular nucleus at one end, a contractile vacuole 

 at the other. At the anterior end there is often added a small red 

 or brown pigment spot (fig. 134), apparently for the recognition 

 of light, and hence a primitive eye. . At this same pole are also 

 one or two flagella ; when a greater number occur they are scat- 



Fio. 134. 



FIG. 135. 



FIG. 136. 



FIG. 134. Euglena viridis. (After Stein.) c, contractile vacuole^ n, nucleus ; o, pig- 

 ment spot. 



FIG. 135.Dinobryon sertularla. (After Stein.) a, a parasitic flagellate often found in 

 the lorica; ft, contractile vacuole; n % nucleus. 



FIG. 136. Conocladium umbellatum. (After Stein.) 



tered over the body. The body surface is frequently naked, and 

 may be capable of aniceboid motions; at other times it is covered 

 with a more or less evident cuticle. Very common are closed 

 envelopes and open goblet-shaped cases (loricse, fig. 135), and 

 also simple or branched stalks (fig. 136), on which the animals 



