434 BULLETIN" 120, UNITED STATES NATIONAL MUSEUM. 



plied, but that this is probably <lue to the fact that they are enclo- 

 parasites and that it is difficult to furnish them natural environ- 

 mental conditions in artificial cultivation. 



Fabre-Domerojue (1887) refers to Biitschli's (1887-1889) studies 

 cf protoplasmic structure in Opalina. 



Stokes (1888) describes and figures Opalina {Cepedeaf] fiava. 

 The description is insufficient for the recoofnition of the species. 



Fabre-Domergue (1890) refers to the absence of contractile vacuole 

 in OpaliTia ranarum. 



Shewiakoff (1886) gives full reference to Opalina -ranarum (fig- 

 ure, 0. ohtrlgona^ O [Cepedea^ dimidiata (figure), 0. [Cepedeaf] 

 -fiava, O. [Protoopalinal intestinalis and O. [ProtoopaUna] caudata 

 (figure). Cilia and cytoplasm are described; mouth, anus, and con- 

 tractile vacuole are said to be lacking. " The macronucleus [ !] con- 

 sists, in a majority of species, of many discoidal [spherical, ellip- 

 soidal or pear-shaped, not discoidal], round nuclei, scattered without 

 any order through all the endoplasm. Each nucleus contains small, 

 highly refractive nucleoli [one true nucleolus in each nucleus. The 

 reference here may be to the macrochromatin masses]. In two 

 species {intestinalis and caudata) there are in addition to many nuclei 

 [he must mean here the endospherules] one macronucleus consisting 

 of two spherical or oval portions united by a fine thread [this must 

 mean the two nuclei]. Apparently there is no micronucleus. Move- 

 ments not especially quick, body very supple, not contractile, nutri- 

 tion by endosmosis over whole surface of body, transverse and 

 oblique fission (" very probably the so-called oblique division is 

 nothing less than conjugation"), encystment, several nuclei in the 

 cj'sts at first, after they have lain in water a time the cysts have 

 but one nucleus [erroneous] so that the young individuals hatched 

 from the cysts have but one nucleus. [The number varies from 1 to 

 12 or so; they have the same number with which they entered the 

 cysts.] There are literature and synonomy lists for each of the 

 six species described. Cepedea dimidiata, Protoopalina intestinalis 

 and P. caudata are mistakenly described as a little flattened. There 

 is an extended discussion of the history of the taxonomy of the 

 Ciliata in which the classification of the Opalinids by diiferent 

 students is given. Some of those whose classifications of Opalinidae 

 are mentioned are Ehrenberg (1831 and 1838), Dujardin (1841), 

 Perty (1852), Stein (1859), Claparede and Lachmann (1868), Kent 

 (1881-1882), Biitschli (1880-1889, Infusorian part 1887-1889). ' 



Entz (1888) mentions several systems of classification, by different 

 authors, including the Opalinids: he refers to Engelmann's (1876) 

 opinion that the nucleuslike structures in Opalina ranarum are true 

 nuclei, but that O, ranarum., like other multinucleate ciliates, is still 

 unicellular. The rodlike bodies may be trichocysts as Allman and 



