290 C. CLIFFORD DOBELL. 
The formation of zoospores in Radiolaria was described by 
Hertwig, but in more detail by Brandt, whose results have 
become fully known during only the last few years (’02, 05). 
It appears from his researches (e.g.in Thalassicolla) that 
the entire nucleus fragments into chromidia, which later form 
the nuclei of isospores (asexual reproduction). But in the 
formation of anisospores (probably gametes) only a part of 
the nuclear material goes into chromidia, which subsequently 
form the nuclei of the swarmers. The nucleolus stays behind 
and perishes with the remains of the parent organism (cf. 
mastigamoebee). (T'ext-fig. 6.) 
This account has received confirmation from the work of 
TEXT-FIG. 7. 
Part of a plasmodium of Plasmodiophora brassice. 
N. nucleus; C. chromidia. (After Prowazek, °05.) 
Schouteden (07), who was the first to bring these phenomena 
into line with the other work on chromidia, 
(6) Mycetozoa.—The chief work on chromidia in this 
group has been done by Prowazek (’04a, ’05). He has found 
that the nuclei in the plasmodium of Plasmodiophora 
at one period in their development give up chromatin—in the 
form of chromidia—into the cytoplasm, and then after under- 
going further changes give rise to gamete nuclei (text-fig. 7). 
Conjugation takes place as the spores are formed. Chromidia 
therefore take part in the vegetative existence of the orga- 
nism. ‘he sexual process in other Mycetozoais not very well 
known. But recent work (Pinoy, ’08) has shown that in one 
case at least (Didymium) there exist sexually differentiated 
plasmodia from the first. 
(7) Mastigophora.—Chromidia have been described in 
