THE SARCODINA 249 



the animal becomes a pear-shaped flagellate swimming by means of its 

 flagellum (Schewiakoff, 863 ; Caullery, 300). Ciliophrys thus recalls Pseudo- 

 spora in its two- phases (p. 218), and there can be little doubt that the two 

 forms are closely allied. 



Dimorpha nutans, Gruber (Fig. 104), has radiating pseudopodia strengthened 

 by axial rods, and in addition a pair of flagella arising close together at one pole 

 of the body. Both flagella and pseudopodia arise from a centrosome situated 

 near the flagellated pole ; the single nucleus is also excentric and placed 

 close beside the centrosome. The animal uses one of its flagella for attach- 

 ment, while the other remains free (Schouteden). 



These facts appear to indicate an origin for the Heliozoa from Flagellates 

 such as those of the genus Multicilia (p. 270, Fig. 113), in which the body 

 bears radiating flagella planted evenly over the surface ; transformation of 

 the flagella into stiff pseudopodia would produce the Heliozoon - type of 

 organism. On such a view two peculiarities of the Heliozoan pseudopodia 

 receive explanation : the power of nutation and bending which they fre- 



FIG. 104. Dimorpha nutans. After Schouteden. 



quently possess ; and their insertion on a " central grain," which would then 

 represent the blepharoplast, pure and simple, of a flagellate. On this view 

 the pseudopodia of the Heliozoa would appear to be structures quite different 

 in nature from the similarly-named organs of Lobosa. 



On the other hand the Heliozoa also show affinities towards forms classed 

 among the Reticulosa or " Proteomyxa," as already noted in the case of 

 Ciliophrys and Pseudospora. Przesmycki has described a species, Endophrys 

 rotatorium, parasitic in Rotifers, which he considers as a connecting-link 

 between Nuclearia and Vampyrella. The exact systematic position of such 

 genera must be considered at present an open question. 



VI. RADIOLARIA. 



General Characters. The Radiolaria are characterized, speaking 

 generally, by the same type of form and symmetry that is so 

 marked a feature of the Heliozoa, though in many cases the internal 



