Chapter 37 

 Order 1 Holotricha Stein (continued) 



Suborder 6 Apostomea Chatton and Lwoff 



ASYMMETRICAL forms with a rosette-like cytostome through 

 which liquid or small solid particles are taken into the body; 

 sparse ciliary rows spiral; adoral rows short; macro nucleus oval to 

 band-form; a micronucleus; a single contractile vacuole. 



The life-cycle of the ciliates grouped here appears to be highly 

 complex and Chatton and Lwoff (1935) distinguished several devel- 

 opmental phases (Fig. 296), as follows: (1) Trophont or vegetative 

 phase: right-spiral ciliary rows; nucleus pushed aside by food bodies; 

 body grows, but does not divide. (2) Protomont: transitory stage be- 

 tween 1 and 3 in which the organism does not nourish itself, but pro- 

 duces "vitelloid" reserve plates; nucleus central, condensed; ciliary 

 rows become straight. (3) Tomont: the body undergoes division 

 usually in encysted condition into more or less a large number of 

 small ciliated individuals. (4) Protomite: a stage in which a renewed 

 torsion begins, and which leads to to mite stage. (5) Tomite: small 

 free-swimming and non-feeding stage, but serves for distribution. (6) 

 Phoront: a stage which is produced by a tomite when it becomes at- 

 tached to a crustacean and encysts; within the cyst a complete trans- 

 formation to trophont takes place. 



Family Foettingeriidae Chatton 



Genus Foettingeria Caullery and Mesnil. Trophonts large, up to 1 

 mm. long; sublenticular, anterior end attenuated; dorsal surface con- 

 vex, ventral surface concave; right side less convex than left side; 9 

 spiral ciliary rows nearly evenly arranged; in gastro vascular cavity 

 of various actinozoans; tomont on outer surface of host body, gives 

 rise to numerous tomites with meridional ciliary rows; each tomite 

 becomes a phoront by encysting on a crustacean, and develops into 

 a trophont when taken into gastrovascular cavity of an actinozoan. 

 One species. 



F. actiniarum (Claparede) (Fig. 297, a). Phoronts on Copepoda, 

 Ostracoda, Amphipoda, Isopoda and Decapoda; trophonts in Ac- 

 tinia messembryanthemum, A. equina, Anemo7iia sulcata and other 

 actinozoans in European waters; Chatton and Lwoff found Metri- 

 dium marginatum, Sagartia leucolena and Astrangia danae of Woods 

 Hole free from this ciliate. 



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