INFITSOBIA. 



191 



a latticed shell. The cxtra-capsular cells (yellow bodies) are wanting. Acatittm- 



HK'trtl J>rl/Hi-it!i/ Joll. Miill. 



II. Puhjci/ttaria. Radiolaria which form colonies with several central capsul-'-i 

 Amongst the Sphaerozoa a skeleton is wanting or consists of single pieces not 

 joined together. CvUozmnii 'incrmc, K. Haeck. X/iIttrrnzomit jiii/trfiifmn, Joh. 

 Miill. In C'<>lloxj)!ie/->-tr the skeleton consists of simple latticed spheres, each <>f 

 which encloses a central capsule, Colloxjth (/!<( Hu-rleiji Joh. Miill. 



FIG. 132. Eucyrtidium cranoides (after E. Haeckel) 



CLASS II. INFUSORIA.* 



Protozoa with a definite form, and provided with on external 

 membrane, bearing either flag etta or cilia. Mouth and anus usually, 

 contractile vacuole and one or more nuclei ahuays present. 



Infusoria were discovered towards the end of the 17th century 



* Ehrenberg, " Die Infusionsthierchen als vollkommene Organismen." 1838. 

 Balbiani, "Etudes sur la Reproduction des Protozoaires," J/nini. dr In Phyx.. 

 Torn. III. Balbiani, '-Recherches sur les phenomenes sexuels des Infusoires," 



