138 



THE RADIOLARIA 



by rapid division of the capsule and endoplasm. The ectoplasm 

 fragments and the products are disseminated through the water. 

 Each minute product consists of several nuclei lying in a pigmented, 

 oily fragment of endoplasm and supported by a portion of the 

 original ectoplasm. The further history of these bodies is unfortu- 

 nately not known. 



Cc 



FIG. 21. 



Multiple fission in Thalassophysidae. (After Brandt.) A, central capsule and nucleus of 

 Th. spiculosa, x 40. B, section of the nucleus to show the two zones of nucleoplasm and the 

 vermicular nucleoli in the outer layer, x 66. C, Th. pelagiea about to divide ; the nucleus has 

 undergone fragmentation. D, multiple fission of the central capsule of Th. pelagica. E, 

 enlarged view of a portion of the same, x 200. F, stained portion of capsule of the same ta 

 show nuclei before fragmentation of the capsule. G, division of central capsule of Th. sanguino- 

 lenta, x 7. C.e, central capsule ; N, nucleus of vegetative individual ; NI, nucleus of frag- 

 menting individual ; On, In, outer and inner zones of endoplasm. 



The separation of a portion of the Radiolarian organism as a- 

 bud is a rare phenomenon, of which the " extracapsular bodies " of 

 the Sphaerozoidae offer the best example. These structures occur 

 in small colonies of Cullozoum inerme, C. radiosum, C. fulmim, and of 

 Sphaerozoum neapolitanum. They consist of a lobate, highly refrac- 

 tive, cytoplasmic mass, containing a group of modified nuclei 

 ranged about a grape-shaped mass of fat, and are loosely attached 

 to the colonial jelly (Fig. 22). These extracapsular bodies are 

 budded off from the endoplasm of certain members of the colony in 

 which they occur, and are at first uninuclear. According to Brandt's- 



