MORPHOLOGY 



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trichocysts or trichites, depending upon their position (or environ- 

 ment) and the phase of development of the organism. 



Although the trichocyst was first discovered by Ellis (1769) 

 and so named by Allman (1855), nothing concrete is yet known as 

 to their function. Ordinarily the trichocysts are considered as a de- 

 fensive organella as in the case of the oft-quoted example Parame- 

 cium, but, as Mast demonstrated, the extruded trichocysts of this 

 ciliate do not have any effect upon Didinium other than forming a 

 viscid mass about the former to hamper the latter. On the other 



Fig. 23. Diagrams showing the formation of trichocysts in Gymnodini- 

 oides (a-c) and in Polyspira (d) and of trichites in Foettingeria (e) (Chat- 

 ton and Lwoff). a, a ciliary row, composed of kinetosomes, large satellite 

 corpuscles and kinetodesma (a solid line); b, each kinetosome divides into 

 two, producing trichocystosome; c, transformation of trichocystosomes 

 into trichocysts; d, formation of trichocyst from one of the two division 

 products of kinetosome; e, formation of trichites from the division prod- 

 ucts of kinetosomes. 



hand, the trichocysts and trichites are clearly an offensive organelle 

 in capturing food organisms in organisms such as Dileptus, Didinium, 

 Spathidium, etc. Saunders (1925) considered that the extruded tri- 

 chocysts of Paramecium serve for attachment of the body to other 

 objects. But Wohlfarth-Bottermann (1950) saw Paramecium cauda- 

 tum extruding up to 300 trichocysts without any apparent external 

 stimulation and trichocyst-less individuals were able to adhere to 

 foreign objects. This worker suggested that the trichocyst secretes 

 calcium salt and probably also sodium and potassium, and thus may 

 serve an osmoregulatory function. Some years ago Penard (1922) 

 considered that some trichocysts may be secretory organellae to pro- 

 duce material for loricae or envelope, with which view Kahl concurs, 

 as granular to rod-shaped trichocysts occur in Metopus, Amphilep- 



