32 



MANUAL OF ZOOLOGY 



Radiolaria which give rise to colonies are exceptional, but 

 a few cases occur. In these (Fig. n) the central capsule 

 divides again and again giving rise to a number of central 

 capsules which remain embedded in a firm gelatinous sub- 



stance — the vacuolated protoplasm outside the central cap- 

 sules. Such a mass, which may attain considerable size, 

 floats about freely in the sea. 



