560 



THE LOWEST ANIMALS. 



body, like sun-rays, as represented in pictures. The common sun - animalcule 

 (Actinophrys) forms a tiny translucent spherical globule, bristling with 

 pseudopods, and about ^io of an inch in diameter. The pseudopods appear stiff 

 but are quite flexible, and the body contains several clear vesicles, one of 

 which is usually half emerged from the body and on the point of bursting ; 

 the nucleus being in the centre of the body. The animal can move over a 

 hard surface by the alternate relaxation and stiffening of its pseudopods, 

 and sometimes so quickly that it appears to run like a spider. When a 

 pseudopod touches some small organism, the latter seems to become paralysed, 

 the pseudopod approximating itself and its prey to the body, which sends up a 



green sun-animalcule, Acanthocystis chcetophora (highly magnified). 



lobe wherein the organism is enveloped. Reproduction commonly takes place by 

 simple division of the animal into two. The common sun - animalcule occurs 

 abundantly amongst the weeds in clear pond-water. The green sun - animalcule 

 (Acanthocystis) figured above is provided with a skeleton composed of fine 

 siliceous rods or rays, the inner ends of which, buried in the body, are tipped with 

 little discs, the outer ends being either simple or forked. 



In another species the siliceous needles are arranged tangentially ; further, 

 the skeleton may be formed of a siliceous latticed sphere, as in the lattice- 

 animalcule (Clathrulina), which grows fixed to aquatic plants by the base of 

 its long flexible stalk. The body sends its long slender pseudopods through the 

 meshes of the lattice; the total length of the animal is about 20^ °f an mc ^- 



