JUIIZOPODA. 



181 



by holes, to shelter and protect the body (Foraminiferd, Radiolaria). 

 In the Infusoria, the sarcode body is bounded by an external mem- 

 brane, and is capable of quick and varied locomotion by means of the 

 movements of the cilia, hairs, bristles, etc., which it possesses. The 

 solid nourishing matter is taken in through a mouth, and the 

 remainder, after digestion, passes out through an anal aperture. 



CLASS I. RHIZOPODA.* 



Protozoa without external investing membrane, the parenchyma of 

 which protrudes and retracts processes ; as a rule, a calcareous shell or 

 silicious skeleton is secreted. 



The body-substance of these animals, the shells of which were 

 described as Foraminifera or Polythalamia, long before their living 

 contents were 

 known, consists 

 of sarcode, and 

 is without any 

 boundary mem- 

 brane. 



The body- 

 substance, 

 which is richly 

 granulated and 

 contains pig- 

 nient, contracts 

 slowly and 

 sends out at the 

 same time fine 

 thread -like rays 



(fi^ 120) for 



the most part 



of a semi-fluid 



cons is te ncy 



(pseudopodia} ; and these serve not only as a means of movement but 



also for the reception of nourishment. The pseudopodia may, how- 



* Dujardin, "Observations sur les Rhizopodes" (Comptes rendits, 1835). 

 Ehrenberg. " Tiber noch jetzt zahlreich lebende Thierarten der Kreidebildung 

 und den Organisms der Polythalamien" (Abhandlung der AJtad. ru Berlin^ 

 1839). Max Sigin. Schultze, " Uber den Organismus der Polythalamien" 

 (Leipzig, 1854). Joh. Miiller. " Uber die Thalassicolen, Polyoystinen und Acan- 

 thometfen" (1858). E. Haeckel, "Die Radiokrien" (Eine Monographic. 

 Berlin, 1 862). 



Flr " 120. Optical section through portion of the sarccde body of 

 Actinosphaerium Eichhornii (after Hertwig and Leaser). N, nuclei 

 j n t, ne endosarc, from which the vacuolated ectoaarc ifl clearly dis- 

 tinguishable. In the centre of the pseudopodia the axial thread is 

 visib'.c. 



