SYSTEMATIC PART. 



CLASS RADIOLARIA. 



Radiolaria, Johannes Miiller, 1858J 

 Rhizopoda radiaria, Johannes Miiller, 1858. 

 Polycystina (pro parte), Ehrenberg, 1838. 

 Echinocystida, Claparede, 1858. 

 Rhizopoda capsularia, Haeckel, 1861. 

 Cytophora, Haeckel, 1862. 



Definition of the Class : R hizopoda with unicellular body, divided 

 by a porous membrane into an internal or intracapsular part 

 (with nucleus), and an external or'extracapsular part (with 

 calymma); propagating by flagellated spores. 



The RADIOLARIA or CAPSULATE RHIZOPODA, first constituted by Johannes Miiller in 

 the year 1858 as a separate group of the Rhizopoda, form a peculiar class of the 

 PROTISTA, or unicellular organisms. This class is exclusively marine, and has in 

 general the characteristic organisation of the Rhizopoda, with the development of 

 numerous pseudopodia from the surface of the cell; but it differs from all other 

 Rhizopoda in the possession of a peculiar membrane, dividing the cell-body into two 

 different parts ; the central capsule or the internal part with the nucleus, and the external 

 part or extracapsulum with the calymma; propagation by flagellated spores produced in 

 the central capsule ; the sarcode or the protoplasm of both parts communicates by fine 

 pores, piercing the separating membrane, which is called the capsule-membrane. 



The Central Capsule or the inner part of the Radiolarian body is constantly composed 

 of three essential parts, viz. : 



1. The Central Nucleus (a true cell-nucleus). 



2. The Intracapsular Sarcode (endosarc) or surrounding internal protoplasm. 



3. The Capsule Membrane or enveloping porous membrane. 



(ZOOL. CHALL. EXP. PART. XL. 1'885.) Er 1 



