THE RADIOLA1UA 



139 



account (10) these bodies have a twofold significance. Either 

 they become additional members of the parental colony and develop 

 central capsules, or they become megaspores and the small parental 

 endoplasm develops microspores. In his later work Brandt lays 

 additional stress on the latter fate. He has not only seen the bean- 

 shaped active megaspores formed by the extracapsular bodies, but 

 (26, p. 264) also the mass of microspores formed by the small 

 capsules which had budded off these bodies : a proterogynous 

 arrangement. It should be added that Brandt affirms very strongly 

 the juvenile nature of these small budding colonies ; whilst Famintzin, 



FIG. 22. 



Collozoum sp. Portion of a colony showing extracapsular bodies (E.C). 

 x 100. (After Brandt.) 



working in the same locality, asserts that their small size is due to 

 fission of full-grown coenobia (13). 



Spore - Formation. Flagellated spores occur in the four main 

 divisions of the Radiolaria, but their exact nature is only known in 

 some Collodaria and some Acantharia, and it is in the former order 

 that their formation has been traced. The process is described for 

 Thalassicotta on pp. 99-102. 



Isospores. The development of isospores in the Sphaerozoa 

 takes place in colonies distinct from those that produce heterospores. 

 After a vegetative life of several months these colonies exhibit 

 characteristic changes (Fig. 25). The nuclei become ranged in a 

 single or double row just beneath the capsular membrane. Without 

 becoming obviously differentiated, these lumps of chromatin divide 

 directly and acquire a doubly refractive character. Hundreds of 



