DERIVED ORGANIZATION— TAXONOMIC STRUCTURES 149 



In many types, especially in Radiolaria, they may be long and ray- 

 like, with relatively little tendency to fuse; in other cases a main 

 trunk gives rise to so many branches that it is lost in the reticulum, 

 great accumulations of protoplasm collecting at the branching points 

 (Fig. 10, p. 32). 



Doflein includes axopodia and these branching anastomosing 

 pseudopodia in the one type (rhizopodia), and sees in the axial fila- 

 ment of the former and the inner protoplasm of the latter only 



Fig. 80. — Clathrulinaelcgans, stalk formation. (After Valkanow, Archiv f. Protisten- 

 kunde, 1928, courtesy of G. Fischer.) 



different states of the same fundamental stereoplasm. Axial fila- 

 ments, however, derived from the substance of kinetic centers, are 

 quite different from structureless axial stereoplasm which has no 

 relation to kinetic elements. The enveloping protoplasm is appar- 

 ently the same in both types and granule streaming is a common 

 property, but the physical consistency is quite different. In rhizo- 

 podia the outer protoplasm is soft and miscible, leading to fusion 

 on contact with one another, while axopodia never anastomose. 

 The denser core of rhizopodia, while not condensed to a single fiber, 

 serves the same function of support as the axial filament of Actino- 

 sphaerium and gives stiffness and rigidity to long ray-like pseudo- 



