THE INFUSORIA 439 



5. Separation of the conjugants '; division of the synkaryon to 

 form a new micronucleus and macro nucleus. 



Classification. The Ciliata are divisible into two sections, which 

 comprise in all four orders : 



Section A. Aspirigera. 



Without a spiral zone of adoral cilia or membranellae. 



ORDER I. : HOLOTRICHA. Cilia of approximately even length all over 

 the body, forming a continuous, evenly- distiibuted coat in more primitive 

 forms, arranged in bands or restricted to special regions in more specialized 

 forms. 



Suborder 1 : Astomata. Mouthless forms of parasitic habit. Opalina, 

 Anoplophrya, Discophrya, etc. (see p. 451). 



Suborder 2: Gymnostomata. Mouth a simple pore, near or at the anterior 

 pole of the body, leading into a simple, usually straight oesophagus without 

 cilia or undulating membranes, often with a rod-apparatus by which the mouth 

 is closed and opened for food-ingestion. 



Classified in various ways ; three families recognized by Doflein (7) : 



(1) Enchelidce, including Holophrya, Prorodon (Fig. 14), Coleps, Didinium, 

 etc. ; Buetschlia, parasitic in the rumen of ruminants. To the family Enche- 

 lidce must be referred, apparently, the remarkable form described by Meunier 

 under the name Gymnozoum viviparum, which is stated to have the following 

 characteristics : The surface of the body bears no cilia, which appear to be 

 wanting altogether in this form ; the mouth- opening is at one extremity of 

 the ovoid body, and contains an extrusible proboscis, used for the capture 

 of prey (see p. 442) ; the micronucleus is contained within the macronucleus ; 

 reproduction is by transverse fission, and also by internal budding, producing 

 embryos which may produce in their turn other embryos in a similar manner 

 before being liberated from the parent body, from which they are set free by 

 dehiscence. (2) Trachelidce, including Trachelius, Trachelocerca, Amphileptus, 

 Lionotus, Loxodes, Dileptus, etc. (3) Chlamydodontidce, including Chilodon 

 (Fig. 184), Nassula, etc. (4) F cettingeriidce (Chatton, 831'5): F ccttingeria, 

 Perikaryon. 



Suborder 3 : Hymenostomata. Mouth usually at the side of the body and at 

 the bottom of a peristomial depression, leading into a short oesophagus never 

 supported by a rod-apparatus, but containing an undulating membrane; 

 consequently not capable of being closed, but permanently open. 



Families: (1) Chiliferidce : Leucophrys, Glaucoma,, Frontonia, Colpoda, 

 etc. (2) Paramecidce : Paramecium (Fig. 185), etc. (3) Pleuronemidce : 

 Pleuronema (Fig. 27), etc. (4) Isotrichidce : Isotricha, parasitic in the rumen 

 of ruminants ; and other families. (5) Microthoracidce : Microthorax, Con- 

 chophrys (Chatton, 831 -5). 



Section B. Spirigera. 



With a conspicuous spiral zone of larger cilia or vibratile membranes leading 

 to the mouth ; oesophagus as in Hymenostomata. 



ORDER II. : HETEROTRICHA. Generally of swimming habit, sometimes 

 sedentary. 



Suborder 1 : Polytricha. Body covered with an even coat of cilia. 



Principal families: (1) Plagiotomidce ; example: Spirostomum (Fig. 180). 



(2) Bursaridce; examples: Bursaria ; Nyctotherus (Fig. 9), with species 

 entozoic in various animals; Balantidium, also entozoic. (3) Stentoridce; 

 example : Stentor (Fig. 8). (4) Tintinnidce (compare Entz, 53) ; examples : 

 Tintinnus, etc. 



Suborder 2 : Oligotricha. Body-cilia greatly reduced or absent. 



Families: (1) Halter idee ; example: Halteria. (2) Ophryoscolecidce, with 

 numerous genera parasitic in the stomachs of ruminants ; examples : Ento- 

 dinium, Ophryoscolex, Cycloposthium. 



