THE OPALINID CILIATE INFUSORIANS. 433 



plication seems to be that Bronn would regard them in the same way, 

 as developmental forms of other organisms, an opinion already ex- 

 pressed by Max Schultze (1851) as well as Stein (1854, 1856). 



Hoffer (1872, or later) quotes from Ley dig the statement that 

 Opalina ranarutn is multinucleated, but the true nuclear nature of 

 the bodies is questioned. The opinion is expressed that, if they be 

 true nuclei, Kolliker's and Schultze's interpretation of the Opalinas 

 as developmental stages of higher organisms is more probable. 

 Opalina dimidiata and O. obinqona also are mentioned. Under 

 Ciliata Holotricha he places " I Fam. Opalinina (wahrscheinlich zum 

 grossten Theile keine Infusorien)" including the genera OpaUna^ 

 Hoplitophrya^ Anoplophrya^ Tlaptophmja. 



Kent (1880). Reference is made to the Opaninidae, including the 

 astomatous Ciliata, among them being Opalina, "the simplest of 

 them all." The contractile vacuole is said to be absent ; the nuclei are 

 recognized, and the growth from the uninucleate condition of " young 

 forms " to the multinucleate " adult " is mentioned. There are five 

 figures of 0. ranarum, "adult," cyst, transverse [?] fission, and what 

 appears to be a microgamete mother-cell. [The latter must have been 

 from a tadpole, if it be a mother-cell.] 



Balbiani (1881) mentions absence of mouth and anus in '■'' Opa- 

 lina^"^ limiting the genus to the forms parasitic in Batrachians. 



Kent (1881-1882). In the reference to this book, in the author's 

 previous revicAv of the literature, Metcalf (1909), it Avould have been 

 well to have quoted Kent's classification of Opalina, as follows: 



Appendix A. — Holotricha-Astomata. 



Contractile vesicle absent, 1 

 endoplast rarely conspicu- > "Opalina" 

 ous ) 



One or more contractile vac- 1 

 uoles, endoplast conspicu- > Anoplophrya 

 ously developed I 



i Prehensile organs acetabuli- \ Haptophrya 

 form / 



Prehensile organs unciform } IloplUophrya 



Kent's use of the name Opalina covers only the four present genera 

 Protoopalina, Zelleriella, Cepedea, and Opalina. 



Blochmann (1886) refers to the members of the genus Opalina as 

 lacking mouth, anus, and contractile vacuole, as possessing numerous 

 regularly distributed small nuclei, and as occurring in the recta of 

 native [German] frogs and toads. No figures. 



Gruber (1886) describes as the common method of reproduction m 

 Opalinas the fragmentation of the body into small pieces and the 

 subsequent growth of these pieces to normal animals. He says it is 

 noteworthy that these very organisms can not be artificially multi- 



Fam. XIII, Opalinidea; 

 animalcula finely and 

 evenly ciliate through- 

 out; endoparasitic, pos- 

 sessing no distinct oral 

 aperture 



Simply ciliate, possessing 

 no special prehensile or- 

 gans 



