THE RADIOLARIA. 



83 



or "vacuoles," which, rhythmically, become distended with 

 water, and are then obliterated by the contraction of the sur- 

 rounding protoplasm. But in the Actinophrys (or more 

 properly Actinosphcerium) Eichornii (Fig. 4), the central 

 part of the protoplasm is distinguished from the rest by con- 

 taining a number of endopiasts. It thus leads to the Hadiola- 

 ria (Polycistina of Ehrenberg), the simplest forms of which 



~Fm. 4.— Actinosphcerium Eichhornii (after Hertwig and Lesser, " Ueber Rhizopo- 

 den," Scbulze's Archiv, 1876). 



I.— The entire animal; c, c, contractile vacuoles. . . 



II.— Part of the periphery much magnified; a, a, a, pseudopodia with stiff axial sub- 

 stance; n, nuclei or endopiasts. , . , ■, t 



III.— A very young Actinosphcerium, with only two nuclei and two pseudopodia, 

 much magnified. 



eonsist essentially of a myxopod provided with filamentous, 

 radiating, and often anastomosing, pseudopodia. The centre 

 of the body is occupied by a capsule filled with protoplasm ; 



