470 PROCEEDINGS OF THE NATIONAL MUSEUM vol.87 



and the female gamete each contribute the same number of nucleoli 

 and that the zygote contains the double number. In several other 

 species of opalinids an odd number of nucleoli seems to be present. 

 How shall the puzzle be resolved? Chen (1936b) has shown that 

 when two or more nucleoli are close together they may fuse into a 

 single body. This offers a plausible explanation. 



I have tried for a number of years to get material for restudy of the 

 sexual phases of the life-history in some Protoopalina, preferably the 

 Protoopalinas of Bomhina, the fire toad, either P. intestinalis or P. 

 caudata, but repeated attempts have failed. The Bombinas, although 

 successfully imported and living for more than a year in vivaria, do 

 not breed. When freed by the dozens into apparently suitable environ- 

 ments they are not seen again. 

 And freshly imported specimens, 

 arriving before the eggs are laid, 

 do not breed or even copulate, and 

 if set free disappear. The restudy 



Figure 2i.— "Protoopalina caccosterni" Fantham, of the SCXUal phenomena mUSt 



xioo. (After Fantham.) apparently be done in Europe if 



Protoopalina is to be used, but Zelleriella might be better as shown 

 by the recent work of Chen (1936a and b). Metcalf (1909) failed to 

 distinguish between the real chromosomes and other nuclear structures. 



Items of interest to take into account in connection with Fantham's 

 report of three nucleoli in daughter nuclei of P. caccosterni are: (a) The 

 appearance of three nucleoli in daughter nuclei of P. ovalis (fig. 30) 

 and of five nucleoli in the nuclei of several multinucleate species; (b) 

 the presence of one large and three small nucleoli in each nucleus of 

 P. axonucleata lata (see Metcalf, 1923a), the nucleoli not being in pairs, 

 and of P. meridionalis (fig. 28) ; (c) the presence of one large nucleolus 

 and a chromatin skein in the nuclei of cysts and of young forms of 

 Opalina chattoni (Weill, 1929); (d) the presence of one large nucleolus 

 and of scattered small chromatin granules in nuclei of adults of 0. 

 nucleolata (p. 538); (e) the transverse division of nucleoli in Protoopalina 

 intestinalis and P. caudata at about the time of the ill-defined equa- 

 torial plate stage (Metcalf, 1909), and the appearance of longitudinal 

 splitting of the nucleolus in the telophases of the same nuclei (Metcalf, 

 1909, cf. Konsuloff, 1922); [Are the apparently daughter nucleoli in 

 the anaphases and telophases in Protoopalina really double?] (f) the 

 origin of the nucleoli in the postsexual stages of the life history. These 

 and other items should be studied. 



We should realize that "P. caccosterni" is reported only from tad- 

 pole hosts. It may not be a Protoopalina at all but may be the 

 Protoopalina-stage in the development of a Cepedea or an Opalina, 

 though this is very unlikely, since no individuals with more than two 



