20 



PKOTOZOANS. 



5. An oblique groove (peristome) extending from the 

 anterior end halfway along one side of the animal, and so 



twisted that its edges form an 

 elongated 8-shaped figure when 

 viewed from the side (see cut). 



6. A fringe of cilia, longer and 

 stronger than those of the body, 

 all around the edge of this groove. 

 These set up currents in the water, 

 which may be seen, if there be any 

 loose sediment in the water, set- 

 ting to Ward the posterior end of 

 this groove. 



7. A funnel-shaped chamber 

 (vestibule, or mouth) in the poste- 

 rior end of this groove. Toward 

 this the currents in the water tend, 

 and into it they drive the particles 

 they sweep along. 



Near to this chamber, and in 

 the central portion of the body, is 

 an elongated, often spindle-shaped 

 nucleus, often hardly visible with- 

 out staining. 



In one or two places in the body 

 there is a clear, round spot of con- 

 siderable size (usually one near 

 each end), which regularly ap- 

 pears and quickly disappears sev- 

 eral times a minute. Each of these 

 is a contractile vesicle. If one of 

 these be watched very closely, it 

 will be seen to have minute, radi- 

 ating tubes appearing around it when it contracts. 



The remaining objects seen in the endosarc are food 



PARAMEOIUM fx300). The 

 water current is driven in 

 the direction of the large 

 arrow by the lashing ac- 

 tion of the cilia of that re- 

 gion. Food particles pass 

 down the funnel-shaped 

 esophagus (e), and col- 

 lect in little round pellets 

 at the bottom. Then they 

 circulate about the body 

 in the direction of the 

 arrows, and indigestible 

 portions are ejected at . 

 Two contractile vacuoles 

 (t>) are seen near the ends 

 of the body, and an elon- 

 gate nucleus (ri) may be 

 seen after staining. 



