CV-, 



Fio. 185. Paramecium caudatum: scmi-diagrammatio figure to show the structure. 

 P., peristomial groove ; o, mouth ; <KS., oesophagus, containing an undulating 

 membrane (u.m.) ; f.v.', food-vacuole forming at the base of the oesophagus ; 

 f.v.,f.v., other food-vacuoles circulating in the endoplasm ; c.v., c.v., the two 

 contractile vacuoles, showing a different condition in each, the upper one full 

 and ready to empty itself, the lower one beginning to fill after a contraction ; 

 ex., excretory crystals in the endoplasm ; N, macronucleus ; n, micronucleus ; 

 tm., triohooysts ; al. t alveolar layer ; p., pellicle. After Lang (10), slightly 



