76 PROTOZOOLOGY 



tus, etc. Klein has called these ectoplasmic granules protrichocysts, 

 and in Prorodon, Kruger observed, besides typical tubular tricho- 

 cysts, torpedo-like forms to which he applied the same name. To 

 this group may belong the trichocysts recognized by Kidder in Con- 

 chophthirus mytili. The trichocysts present in certain Cryptomonad- 

 ina (Chilomonas and Cyathomonas) are probably homologous with 

 the protrichocysts (Kruger, 1934; Hollande, 1942; Dragesco, 1951). 



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 Ahthophysis, Maryna, etc., the dendritic stalks are 

 made up of gelatinous substances rich in iron, which gives to them a 

 reddish brown color. In parasitic Protozoa, there are special or- 

 ganellae developed for attachment. Many genera of cephaline 

 gregarines are provided with an epimerite of different structures 

 (Figs. 235-237), by which the organisms are able to attach them- 

 selves to the gut epithelium of the host. In Astomata, such as Into- 

 shellina, Maupasella, Lachmannella, etc., simple or complex pro- 

 trusible chitinous structures are often present in the anterior region ; 

 or a certain area of the body may be concave and serves for ad- 

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

 there may be a distinctive sucker-like organella near the anterior 

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

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



In the Myxosporidia and Actinomyxidia, there appear, during 

 the development of spore, 1-4 special cells which develop into 

 polar capsules, each, when fully formed, enclosing a more or less 

 long spirally coiled delicate thread, the polar filament (Figs. 279, 

 286). The polar filament is considered as a temporary anchoring or- 

 ganella of the spore at the time of its germination after it gained 

 entrance into the alimentary canal of a suitable host. In the Micro- 

 sporidia, the filament may or may not be enclosed within a capsule 

 (Figs. 288; 289). The nematocysts (Fig. 132, b) of certain dino- 

 flagellates belonging to Nematoidium and Polykrikos, are almost 

 identical in structure with those found in the coelenterates. They 

 are distributed through the cytoplasm, and various developmental 

 stages were noticed by Chatton, and Kofoid and Swezy, which indi- 

 cates that they are characteristic structures of these dinoflagellates 

 and not foreign in origin as had been held by some. The function of 

 the nematocysts in these protozoans is not understood. 



