80 



ZOOLOGY 



SECT. 



protoplasm : they then contract, discharging the water into the 

 vacuole, the latter rapidly enlarging while they disappear from 



B 



TClC ^,'fa 



luc. C/T: 



c.vac. - 



im. 



FIG. CO Paramoecium caudatum. A, the living animal from the ventral aspect ; B, the 



ame in optical section: the arrow shows the course taken by food-particles ; (', a specimen 



which has discharged its trichocysts ; D, diagram of binary fission; Ice. gr. buccal groove; 



cart, cortex ; CK. cuticle ; c. vac. contractile vacuole ; /. rue. food vacuole ; iiul. gullet ; rued. 



medulla; ,i .'. inegauucleus ; pa. -/( it.micronucleus; trek, trichocysts. (From Parker's Biology.) 



view ; finally the vacuole contracts and discharges its contents 

 externally. 



The cortex contains minute radially arranged sacs called 

 (//'<:]/.). When the animal is irritated, more or fewer of 



