H 



A. XI MA I. /l/O/.OGY 



ages on its surface, called cilia (Latin, eyelashes) (Figs.). 

 The cilia, like the pseudopods of the ameba, are merely 

 prolongations of the cell protoplasm, 

 but they are permanent. The sepa- 

 ration between the outer ectoplasm 

 and the interior granular endoplasm 

 is more marked than in the ameba 

 (Fig. 14). 



Nucleus and Vacuoles. — There is 

 a large nucleus called the macro- 

 nucleus, and beside it a 

 smaller one called the 

 micronucleus. They are 

 hard to see. About one 

 third of the way from 

 each end is a clear, pul- 

 sating space (bb. Fig. 

 15) called the pulsat- 

 ing vacuole. These 

 spaces contract until 

 they disappear, and then 

 reappear, gradually ex- 

 panding. Tubes lead from the vacuoles which probably 

 serve to keep the contents of the cell in circulation. 



Feeding. — A depression, or groove, is seen on one side, 

 this serves as a mouth (Figs.). A tube which serves as a 



gullet leads from the 

 mouth-groove to the in- 

 M <>. terior of the cell. The 

 mouth-groove is lined 

 with cilia which sweep 



food particles inward. 

 Fig. 16. — Two Paramecia exchanging 



parts of their nuclei. The particles accumulate 



Fig. 14. — Paramecium, 



show ing cilia, c. 



Two contractile vacuoles, cv; 

 the macronucleus, mg\ 

 two micronuclei, mi; the 

 gullet (<2T), a food ball 

 forming and ten food balls 

 in their course from gullet 

 to vent, a. 



