398 BIOLOGY OF THE PROTOZOA 



Class II. SUCTORIA, Butsciili. 



(Also called TentaciiJijcru or Acinctaria). 



Ill one interesting genus of the Suctoria— //?/2.'Ofo//(rt— the ventral 

 surface bears a coating of permanent cilia (Chatton regards this form 

 as an aberrant holotrich see p. 373). In all other genera cilia are 

 confined to the buds or embr\'os during their free-swimming stages 

 and are lost with the acquisition of tentacles and development of 

 the attaching disc or the stalk. The individuals of the group are 

 characteristically sessile and are attached to foreign objects usually 

 by stalks which are short or long, slender or clumsy, but invariably 

 rigid. Floating or suspended forms are exceptional (Sphoerophrya). 

 Tentacles are always present (a single one in Ili/poroma) and may 

 be of two kinds, one suctorial, the other sharp-pointed and adapted 

 for piercing (Ephelotidse, Fig. 1()3, p. 372). The general form of 

 the body is highly varied, sometimes spherical, spheroidal or ellip- 

 soidal; sometimes tetrahedral, occasionall\' branched and ramifying. 

 Houses or tests are frequent. The tentacles may be distributed all 

 over the body or may be confined to limited regions. Reproduction 

 occurs by equal division or by budding, the latter being the more 

 characteristic method. Budding may be either exogenous, i. e., 

 superficial, or endogenous. In the latter case one or more buds 

 may be formed in the protoplasm about one or more micronuclei 

 and a part of the macronucleus (Fig. 1 12, p. 231 ) ; these buds develop 

 cilia in the brood pouch covered over by the anterior cell wall, and 

 when fully formed pass out of the birth opening as ciliated embryos. 

 After a swarming stage of variable duration they become attached 

 and metamorphose into the adult form, or they enter other Protozoa 

 where as parasites they live until metamorphosis occurs. 



Fertilization processes have been worked out in but few forms. 

 In Dcndrocometcs conjugation follows the general plan of conjuga- 

 tion in the ciliates, but, as in the filiate Anoplophrya hranchiarum, 

 there is an interchange of macronuclei as well as of micronuclei. 



Classification of the Suctoria is still imperfect very little having 

 been done in this direction since Collin's masterly monograph (1911) 

 on these forms. We follow Collin in grouping them in eight families 

 as follows: 



Family 1. Podophryidae. — In these forms the body is monaxonic 

 with a tendency to bilateral symmetry. Tentacles are of the 

 suctorial type onl\' distributed over the entire body or grouped in 

 fascicles. The cells are naked or enclosed in tests which may be 

 either delicate and close-fitting with an almost invisible rim, or 

 coarse, loose-fitting with a conspicuous rim. Individuals are 

 usually free-living but may be parasitic. I{e])roduction is by divi- 

 sion or by exogenous budding. 



