CHROMIDIA AND THE BINUCLEARITY HYPOTHESES. 2938 
too doubtful a nature to allow of any profitable discussion 
regarding them. 
(8) Ciliata.—The best instance of chromidia playing a 
part in the life-cycle of a ciliate is to be seen in Opalina, 
(Neresheimer, ’07) (text-fig. 9). At a certain period in its 
development Opalina extrudes chromidia from its nuclei 
into the cytoplasm. The chromidia then collect themselves 
at various points, and so build up new nuclei—the original 
nuclei perishing. These secondary nuclei, after undergoing 
a chromatin reduction, become the nuclei of gametes. The 
history of the chromidia in this animal is therefore rather lke 
a multiple version of that in Thalamophora. 
Trxt-Fig. 10. 
Degenerating fragments of Opalina, with nuclei in a chromidial 
condition. (The large bodies surrounded by a pale area are 
“eosinophil” bodies.) (After Dobell, ’07a.) 
Chromidia are also formed in Opalina—as in many other 
Protozoa—during degeneration (Dobell, ’07a) (text-fig. 10). 
Gonder (05) has given a description of remarkable chro- 
midial phenomena in Opalinopsis and Chromidina. I 
have re-investigated these forms (Dobell, ’08d) and arrived 
at a very different conclusion from Gonder’s. There is no 
complicated series of chromidial changes in Opalinopsis 
during division. The nucleus is in the form of a network 
(‘chromidial net” if one likes to call it so, though there is 
no evidence that it is in any way homologous with the 
chromidial net of Thalamophora), and remains so during 
division. In Chromidina the nucleus is also in the form of 
