OPALINID CILIATE INFUSORIANS — METCALF 615 



and suggest the utility of the Greek word for guest, ^evos, in forming 

 names for parasites. 



In the same year Kudo (1922) refers to Opalinas from adult Rana 

 clamitans and R. pipiens as seemingly identical with 0. ranarum. 

 [0. ranarum has not been found in America. Adult R. clamitans is but 

 very rarely infected.] 



Konsuloff (1922) was inadequately referred to in Metcalf (1923a). 

 His paper is based chiefly upon 0. ranarum and 0. [Ccpedea] dimidiata; 

 anisogamy is described, also encystment of quite large multinucleate 

 individuals; division of endosarc spherules is described [confirmed by 

 Horning, 1925]; 0. ranarum has much-branched excretory canals in 

 the posterior part of the body; the endosarc spherules are called 

 macronuclei [erroneous, see Tonniges, 1927]; the author confirms the 

 opinion that 0. [zelleri] is a form of the species dimidiata; he describes 

 many features of the cytology, also extracellular digestion [but gives 

 no evidence]; in the adults, but not in the tadpoles, the opalinids are 

 said to be positively geo tactic; endogenous cysts were found within 

 encysted adults; the agamonts hatching from these cysts are said to 

 develop directly into adults with no interpolated sexual process [not 

 shown but not improbable] ; the encystment of zygotes is described as 

 normal [the claim being founded, perhaps, on finding binucleate 

 infection cysts, which are quite common] ; the multipUcation of nuclei 

 of encysted zygotes is described [based perhaps on infection cysts 

 with more than two nuclei, which are not unusual, as many as 12 or 

 more sometimes being found. Cf. Brumpt, 1915. Reinfection cysts 

 in the tadpoles, described by Brumpt, might be formed as early in 

 the growth as the zygote stage] ; Metcalf 's classification is confirmed ; 

 there is no formation of nuclei from cliromidia; crystaUine excretory 

 granules in the cytoplasm are mentioned. 



Hegner, in 1922, reported that on a meat diet the tadpoles of 

 R. clamitans, R. pipiens, and Bujo lentiginosus americanus [B. 

 americanus] decrease the number of their opalinids. 



Metcalf (1923a) described about 125 new species of opalinids, 

 mostly from Anura long preserved upon the shelves of the United 

 States National Museum; the geographic distribution of hosts and 

 parasites was discussed, as well as the probable place and time of 

 origin and the times and routes of dispersal with reference to paleo- 

 geographic maps of the successive geologic periods from the Triassic 

 to the present; a critical chronological review of the opalinid litera- 

 ture not included in Metcalf, 1909, was given. 



The same year Metcalf (1923b) discussed the origin and distribution 

 of the Anura on the basis of their opalinid parasites and the geographic 

 distribution of the hosts and parasites. 



Spek, in 1923, described the eft'ects of different salt solutions upon 

 living Opalina ranarum, showing that with changes in the medium 



