84 PROTOZOOLOGY 



tile vacuoles are deeply seated, there is a delicate duct which con- 

 nects the vacuole with the pore on the pellicle as in Paramecium 

 woodruffi, or in Ophryoscolecidae. In Balantidium, Nyctotherus, etc., 

 the contractile vacuole is formed very close to the permanent cyto- 

 pyge located at the posterior extremity, through which it empties its 

 content. 



In a number of ciliates there occur radiating or collecting canals 

 besides the main contractile vacuole. These canals radiate from the 

 central vacuole in Paramecium, Frontonia, Disematostoma, etc. But 

 when the vacuole is terminal, the collecting canals of course do not 

 radiate, in which case the number of the canals varies among 

 different species: one in Spirostomum, Stentor, etc., 2 in Clima- 



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a 



Fig. 27. Diagrams showing the contractile vacuole, the accessory vacu- 

 oles and the aperture, during diastole and systole in Conchophthirus 

 (Kidder). 



costomum, Eschaneustyla, etc., and several in Tillina. In Peritricha, 

 the contractile vacuole occurs near the posterior region of the cyto- 

 pharynx and its content is discharged through a canal into the vesti- 

 bule and in Ophrydium ectatum, the contractile vacuole empties its 

 content into the cytopharynx through a long duct (Mast). 



Of numerous observations concerning the operation of the con- 

 tractile vacuole, that of King (1935) on Paramecium multimicro- 

 nucleatum (Figs. 28, 29) may be quoted here. In this ciliate, there 

 are 2 to 7 contractile vacuoles which are located below the ecto- 

 plasm on the aboral side. There is a permanent pore above each 

 vacuole. Leading to the pore is a short tube-like invagination of the 

 pellicle, with inner end of which the temporary membrane of the 

 vacuole is in contact (Fig. 28, a). Each vacuole has 5-10 long col- 

 lecting canals with strongly osmiophilic walls (Fig. 29), in which 

 Gelei (1939) demonstrated longitudinal fibrils, and each canal is 

 made up of terminal portion, a proximal injection canal, and an 

 ampulla between them. Surrounding the distal portion, there is osmi- 

 ophilic cytoplasm which may be granulated or finely reticulated, and 



