MORPHOLOGY 65 



22) could be distinctly seen and suggested that these trichocysts 

 themselves may be toxic. 



Although the trichocyst was first discovered by Elhs (1769) 

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

 to their function. Ordinarily the trichocysts are considered as a 

 defensive organella as in the case of the oft-quoted example 

 Paramecium, but, as Mast demonstrated, the extruded tricho- 

 cysts of this ciUate do not have any effect upon Didinium other 

 than forming a viscid mass about the former to hamper the latter. 

 Penard considers that some trichocysts may be secretory organel- 

 le to produce material for loricae or envelope,, with which view 

 Kahl concurs, as granular to rod-shaped trichocysts occur in 

 Metopus, Amphileptus, etc. Klein has called these ectoplasmic 

 granules protrichocysts, and in Prorodon, Kriiger observed, be- 

 sides typical tubular trichocysts, torpedo-like forms to which he 

 applied the same name. To this group may belong the trichocysts 

 recognized by Kidder in Conchophthirus mytUi. The trichocysts 

 present in certain Cryptomonadina (Chilomonas and Cyatho- 

 monas) are probably homologous with the protrichocysts. The 

 pigments, which give a beautiful coloration to certain ciliates 

 such as Stentor and Blepharisma, are said to be lodged in the 

 protrichocysts. 



Hold-fast organellae 



In the Mastigophora, Ciliophora, and a few Sarcodina, there 

 are forms which possess a stalk supporting the body or the lorica. 

 With the stalk the organism is attached to a solid surface. In 

 some cases, as in Anthophysa, Maryna, etc., the dendritic stalks 

 are made up of gelatinous substances rich in iron, which gives to it 

 a reddish color. In parasitic Protozoa, there are special organellae 

 developed for attachment. Many genera of cephaline gregarines 

 are provided with an epimerite of different structures (Figs. 181- 

 183), by w^hich the organisms are able to attach themselves to the 

 gut epithelium of the host. In Astomata, such as Intoshellina, 

 Maupasella, Lachmannella, etc., simple or complex protrusible 

 chitinous structures are often present in the anterior region; or a 

 certain area of the body may be concave and serves for adhesion 

 to the host, as in Rhizocaryum, Perezella, etc.; or, again, there 

 may be a distinctive sucker-hke organella near the anterior ex- 

 tremity of the body, as in Haptophyra, Steinella, etc. A sucker is 

 also present on the antero-ventral part of Giardia intestinalis. 



