CILIATE PROTOZOA 

 PARAMECIUM 



The Paramecium caudatum, slipper animalcule (Fig. 20), is 

 a minute animal found in water in which dead leaves or other 

 remains of organisms are decaying. The decay is brought about 

 by bacteria, and upon these the slipper animalcules feed. A 

 rich culture of Paramecium may be obtained by steeping hay 

 in water, allowing it to decay, and adding to the infusion thus 



C.V. 



ec. 



c.v. 





/. 





:: /?=i. 



i i 



A^^' 



.vV 



w^ 



^^- 



f.v. 



u.m. g. 



\ 



an 



Fig. 20. — Paramecium, caudatum,. 



A, An individual seen from the left side, highly magnified; B, a diagrammatic view o an individual 

 from the ventral side, less highly magnified. 



an.. Position of temporary anus ; c.v., contractile vacuole ; ec, ectoplasm with trichocysts ; f.v., food 

 vacuoles ; g., gullet ; meg., meganucleus ; mi., micronucleus pst., peristome ; u.tn., undulating 

 membrane. 



made mud or weeds from a freshwater pond which contains 



Paramecium. The animals may easily be seen with the naked 



eye as minute, greyish white, oblong creatures, moving slowly 



about in the water. The body of Paramecium is spindle-shaped, 



somewhat flattened on one side, and with one end blunter than 



the other. The fiat side is called ' ventral ' and the blunt end is 



anterior. This end appears as though it had been twisted, so that 



a groove which it bears is spiral, starting in front on the left 



and curving round to the ventral side, where it is continued back 



in the middle line to within about a third of the length of the 



body from its hinder end. The groove is known as the peristome : 



from its hinder end there passes backwards into the body a 



46 



