LATTICE WORKERS, OR POLYCYSTINA. 91 



viously described, and yet the riches of the Challenger 

 collection was by no means exhausted. 



From this time the old name of Polycystina came 

 to be absorbed in that of Radiolaria, and the old 

 opinions of structure were modified into something 

 like the following summary of the views propounded 

 by Professor HaeckeL 



The Radiolaria are marine rhizopods, whose one- 

 celled body always consists of two main portions, 

 separated by a membrane, viz., an inner central 

 capsule, with one or more nuclei, and an outer 

 capsule (extra-capsulum), which has no nucleus, and 

 the pseudopodia, the central capsule, is, in part, 

 the general central organ, and, in part, the special 

 organ of reproduction. The outer capsule is partly 

 the general organ of communication with the outer 

 world, and partly the special organ of protection and 

 nutrition. The majority also develop a skeleton, 

 which presents the utmost variety of form, generally 

 composed of silica (or flint), but sometimes of an 

 organic substance. The Radiolarian cell usually leads 

 an isolated existence, but in a small number of in- 

 stances the one-celled organisms are united in colonies. 



It is contended that the special peculiarity of the 

 one-celled organism, by means of which it is distin- 

 guished from all other rhizopods, consists in its 

 differentiation 1 into two separate constituents (the 

 central capsule and the outer capsule) and the forma- 



