CILIATA III 



Entodinium (Fig. 87 B). (Entodiniomorpha.) With three posterior 

 processes, of which the largest is said to serve as a rudder. In the 

 rumen and reticulum of sheep and oxen. Like others of the tribe, 

 these organisms are present in such numbers that they are believed 

 to be symbionts which play a part in the nutrition of the host, render- 

 ing the vegetable food more easily assimilable by feeding on it and 

 being in turn digested further on in the alimentary canal. Infection 

 of the host is probably by cysts on grass. 



Order HYPOTRICHA 



Ciliata with depressed body; a gullet, permanently open and pro- 

 vided with undulating membranes ; an adoral wreath, curving clock- 

 wise ; the dorsal cilia represented only by a few stiff hairs ; and on the 

 ventral side usually an elaborate system of cirri and other ciliary 

 organs. 



The animals can swim but spend much of their time crawling over 

 solid objects by means of the cirri. 



Stylonichia (Figs. 90, 91). A typical example. Common in in- 

 fusions. 



Kerona. With a less highly developed ciliary system than Styloni- 

 chia. Ectoparasitic on Hydra, 



Order PERITRICHA 



Ciliata, for the most part permanently fixed by the aboral surface; 

 with a gullet, permanently open and provided with undulating mem- 

 brane; an adoral wreath, curving counter-clockwise; and on the rest 

 of the body no cilia, save those of an aboral ring in the free-swimming 

 species and stages. 



The conjugation of members of this group has. been discussed on 

 p. 33, their morphology on pp. 104, 105. The anus and contractile 

 vacuole open into the deep vestibule, perhaps owing to an extension 

 of the depression of the ectoplasm which forms the latter. The mega- 

 nucleus is horseshoe-shaped. 



Trichodina (Fig. 87 D). Dice-box shaped; with aboral ring of cilia 

 for swimming, enclosing a ring of hooks for temporary attachment. 

 Ectoparasitic on Hydra and other animals. 



Vorticella (Figs. 2, 92). Shaped like a solid, inverted bell, with, in 

 place of the handle, a stalk which consists of a prolongation of the 

 body, and is clad in a cuticle and contractile by means of a myoneme. 

 Solitary. In fresh waters and marine. 



Carchesium (Fig. 93). As Vorticella, but colonial. In fresh waters. 



Epistylis. As Carchesium, but the stalk is purely cuticular and non- 

 contractile. In fresh waters and marine. 



