72 



PROTOZOOLOGY 



Fig. 21. a, a schematic drawing of the trichocyst of Paramecium cau- 

 datum (Kruger) (b, base of the tip; c, cap; m, membrane; mt, membrane 

 of extruded trichocyst; s, swelling body; t, tip); b, an extruded trichocyst, 

 viewed under phase dark contrast, X1800; c, trichites in Spathidium, 

 spathula, X300 (Woodruff and Spencer); d, a diagram of the trichocyst of 

 Prorodon teres (Kruger) (eg, capsule-granule; e, end-piece of filament; f, 

 filament; w, capsule wall); e, f, normal and extruded trichocysts of Didin- 

 ium nasutum (Kruger). 



