THE OPALINID CILIATE INFUSORIANS. 459 



Opalinids in cultures tend to gather about a bit of rectal contents or 

 rectal wall and even when this is part way up the side of the culture 

 dish. Chemotaxis seems a more probable explanation than geotaxis.] 

 Interesting "Dauercysts" were found in contaminated cultures 

 and in dead frogs ; their structure and the process of their formation 

 is described. The structure of infection cysts and the manner of 

 their formation is described in detail, as are also endogynous in- 

 fection cysts. [Doctor Fortner sent me from Michigan specimens 

 of Opalina ohtrigonoidea in which he had seen apparently the same 

 sort of endogynous cysts. I have not yet studied this material 

 carefully.] 



Accumulation of much reserve nutrition is suggested as the insti- 

 gating cause of the formation of infection cysts in the spring, experi- 

 ments with higher temperatures and with nutrition of the host hav- 

 ing failed to produce encystment. [?] The direct transformation 

 of infection cysts, upon hatching in the tadpoles, into ordinary indi- 

 viduals which grow directly to adults without conjugation, is indi- 

 cated [but not demonstrated] by observations reported. Anisogamy 

 (confirming Metcalf (1909) against Neresheimer (1907)). Imme- 

 diate encystment of zygotes (confirming Neresheimer (1907) against 

 Metcalf (1909) and Brumpt (1915)). [This not very important 

 matter can best be settled by study of isolation cultures.] To our 

 conception of the life cycle of Opalinids Kousuloff adds (1) that 

 copulation cysts [?] must [?] infect a second tadpole before they 

 will develop to adults; (2) that some individuals hatched in the tad- 

 poles from infection cysts develop directly to adults without con- 

 jugation. [Compare Brumpt (1915) , who showed that several cycles 

 of tadpole infection by cysts from tadpoles may occur in one 

 Opalinid life-cycle.] Konsuloff classifies the Opalinids not as primi- 

 tive Ciliates but as secondarily modified forms related to Anoplo- 

 phrya, Hoplitophyra, Discophrya, and Opalinopsis, basing this 

 judgment chiefly upon the [probably erroneous] interpretation of the 

 endosarc spherules as macronuclei. 



In an appendix Konsuloff discusses Brumpt's (1915) paper. Only 

 one point needs mention. He supports the idea of "copulation 

 cysts," against Brumpt's description of the cysts formed in the tad- 

 poles as all reinfection cysts like ordinary infection cysts in adult 

 frogs, by saying that infection cysts of Opalina ranarum have usually 

 from 'six to eight nuclei, while "copulation cysts" have but two or 

 after a time but one. [In my preparations of O. ranarum infection 

 cysts from the adult frog show usually from 1 to 4 nuclei; but there 

 may be as many as 12 ; 1 or 2 nuclei are very common.] 



