OPALINID CILIATE INFUSORIANS — METCALF 619 



Metcalf s studies on the geographical distribution of the opahnids 

 and their hosts. 



Larson and Allen, 1928, reporting again upon rearing of Opalina, 

 said that 80 out of 166 specimens of Rana pipiens were "sufficiently 

 heavily parasitized for use" with Opalina obtrigonoidea. 



Keichenow, 1928, reported that the granules of the nuclei give posi- 

 tive reaction with Feulgen's stain, while the endosarc spherules do 

 not. [There is evidence, some of it unpublished, that nuclear struc- 

 tures which at times react strongly to Feulgen's stain, under other 

 conditions do not.] 



Swarzewsky, 1928, compared sexual and presexual phenomena in 

 Spirochona elegans with those in Opalinidae and euciliates in general. 

 Metcalf, 1928b, discussed, in the light of Boveri's hypothesis as to 

 the fundamental nature of cancer (Boveri, 1914), certain abnormal 

 individuals of Opalina obtrigona, Zelleriella, and Protoopalina caudata. 

 Metcalf, 1928c, discussed, before the American Society of Para- 

 sitologists, parasites and the aid they give in problems of taxonomy, 

 geographical distribution, and paleogeography. (Tliis is but an ab- 

 stract. See Metcalf, 1929a, for full publication.) 



Thompson and Robertson, 1929, made no reference to the Opalinidae, 

 except showing a good, original microphotograph of Opalina ranarum 

 and making the [erroneous] statement that Opalina occurs in nearly 

 every frog. 



Doflein and Reichenow, 1929, give in the third volume of their 

 textbook a full account of recent work by numerous students, with 

 some original drawings. [Metcalf is erroneously reported as having 

 described a Zelleriella stage in the development of Opalina; see p. 

 1164]. The nuclear nature of endosarc spherules is opposed. 



Van Overbeek de Meyer, 1929, after a review of the literature of 

 the Opahnidae, reported: (1) Opalina cysts from adult frogs develop 

 in two ways, one with and the other without interpolation of the 

 sexual process [this is probable but not yet estabhshed by sufficiently 

 guarded, critical experunent]. (2) The term "ectoplast" is preferred 

 to ectoplasma. (3) There are no neurofibrillae in the iimer layer of 

 the "ectoplast.' (4) The basal granules of the ciha arise in situ 

 from a fibril of ectoplast and independently of the nucleus. (5) A 

 fibrillar system develops temporarily as a network of supporting ele- 

 ments, its origin depends upon the state of development of the 

 plasma. (6) The cytoplasm shows during the growth of the animal 

 a definite development by which the number and size of spaces in 

 the plasma slowly increase up to almost the adult condition. After 

 this the cavities become again smaller and fewer, while the plasma 

 connections between become thicker, the plasma thus becoming again 

 compact. During encystment this process is reversed but goes more 



