^ T>TLC*ffV 



c.vac 



Fig. 18. — Paramecium caudatum. A, the living animal from the ventral aspect; 



B, the same in optical section : the arrow shows the course taken by food-particles ; 



C, a specimen which has discharged its trichocysts; D, diagram of binary fission; 

 Sue. gr, buccal groove; cort, cortex; cu, cuticle; c. vac, contractile vacuole; f. 

 vac food vacuole; gul, gullet; med, medulla; nit, meganucleus; pa. nit, micro- 

 nucleus; trek, trichocysts. (From Parker's Biology.) 



47 



