RADIOLARIA 



419 



Peripylea, Actipylea, and Tripylea. Multiple division is also known 

 to occur in Thalassophysidae in which it is the sole known means of 

 reproduction. The central capsule becomes very irregular in its out- 

 hne and the nucleus breaks up into numerous chromatin globules. 

 Finally the capsule and the intracapsular cytoplasm become trans- 



FiG. 194. Diagram illustrating the life-cycle of Actipylea (Kiihn). 

 a, mature individual; b, c, binary fission; d, e, multiplication by budding; 

 f, mature individual similar to a; g, formation of swarmers; h-j, supposed, 

 but not observed, union of two swarmers producing a zygote; k, 1, young 

 individuals. 



formed into numerous small bodies, each containing several nuclei. 

 Further changes are unknown. Swarmer-formation is known in some 

 forms. In Thalassicolla, the central capsule becomes separated from 

 the remaining part of the body and the nuclei divide into a number 

 of small nuclei, around each of which condenses a small avoidal mass 



