RHIZOPODA I FORAMINIFERA. 137 



with one of these threads, it is usually held by adhesion to 

 it, and the filament forthwith begins to retract itself; as it 

 shortens, the surrounding filaments also apply themselves to 

 the captive particle, bending their points together, so as gra- 

 dually to inclose it, and themselves retracting until the prey 

 is brought to the surface of the body ; and the substance of 

 the threads being itself drawn into that of the body, the 

 entrapped particle is embedded along with this, and under- 

 goes digestion in the surrounding sarcode, any indigestible 

 particle being subsequently extruded from the surface of the 

 body, just as 4 in the Amoeba. The reproduction of these 

 creatures, so far as is yet known, is effected by sell-division, 

 like .that of the Infusoria ( 135); but there is reason to 

 believe that a " conjugation," or reunion of two individuals, 

 sometimes occurs, and that this is to be looked on as repre- 

 senting the sexual propagation of higher animals. 



Fig. 78. FORAMINIPERA. 



A, Oolina ; B, C, Nodosaria ; D, Cristellaria ; E, Polystomella ; F, Dendritina , 

 G, Glolngerina ; H, Textularia; I, Quinqueloculina. 



131. This Bhizopod type of animal life is manifested in 

 two groups of great interest, which are characterised by 

 the possession of hard shells, formed by the consolidation 

 of the external layer of sarcode. The Foraminifera have 

 calcareous shells, which often bear a strong resemblance to 

 those of Nautili, &c. in miniature (fig. 78), but which really 

 have an entirely different relation to the animals that form 

 them. For whilst the Nautilus occupies only the last or 

 outer chamber of its shell, the chambers previously formed 



