228 ] The Classification of Lower Organisms 



without micronuclei for more than a year. Macronuclear material is necessary for 

 regeneration, but any fragment of a macronucleus is sufficient. This is a very signifi- 

 cant observation. It means that all the factors controlling the vegetative structure and 

 behavior of a cell can be spread out and intermingled in all parts of a body of con- 

 siderable size; it furnishes an analogy to the state of affairs which may be supposed 

 to exist in bacteria. 



The Ciliophora are treated as two classes, Infusoria and Tentaculifera. Hartog 

 (1909) estimated the number of known species of the former as about five hundred. 

 This number would have included practically all of the fresh-water species known up 

 to the present. Entozoic and marine species were known, but hundreds of species of 

 these ecological groups have subsequently been discovered. Including some two 

 hundred species of Tentaculifera, the phylum Ciliophora appears to be of about 

 twelve hundred known species. 



Class 1. INFUSORIA Lamarck 



Class Ciliata Haeckel Gen. Morph. 2: Ixxviii (1866). 

 Class Ciliatea Hall Protozoology 333 (1953). 

 Further synonymy essentially as of the name of the phylum. 



Ciliophora lacking tentacles, bearing cilia or modified cilia in the mature condition. 



Stein (1867) provided four orders of Infusoria. These orders are surely natural. 



Subsequent authors have proposed many modifications of Stein's system, and many 



of these are surely sound; but among groups proposed as additional orders, only the 



opahnids are positively entitled to this status. 



1. Nuclei all alike, commonly numerous. Order 1. Opalinalea. 



1. Nuclei diflferentiated into macronuclei and 

 micronuclei. 



2. Without a spiral band of membranelles 



or cilia about the cytostome Order 2. Holotricha. 



2. With a spiral band of membranelles or 

 cilia about the cytostome. 

 3. The spiral sinistrorse. 



4. Not of the character of the fol- 

 lowing order Order 3. Heterotricha. 



4. Flattened, cirri and most cilia 



confined to the ventral surface Order 4. Hypotricha. 



3. The spiral dextrorse Order 5. Stomatoda. 



Order 1. Opalinalea nom. nov. 



Suborder Opalininea Poche in Arch. Prot. 30: 250 (1913). 



Protociliata Metcalf in Anat. Record 14: 89 (1918) and Jour. Washington Acad. 



Sci. 8: 431 (1918). 

 Subclass Protociliata Kudo Handb. Protozool. 335 (1931). 

 Order Opalinida Hall Protozoology 113 (1953), preoccupied by family Opalini- 

 dae Claus. 

 Nuclei not differentiated into two types; cilia abundant, undifferentiated; sexual 

 reproduction by the complete union of differentiated minute uninucleate gametes. 

 Commensal in the gut of amphibia and fishes. 



The group has been treated monographically by Metcalf (1923). A single family 

 is usually recognized. 



