IIOW ANIMALS EAT. 
51 
Fig. 15.—A Rhizopod (Rotalia Vmetn ), 
with psetidopodia extended, x 30. 
(2) Solids. —When the food is in solid masses, whether 
floating in water or not, the animal is usually provided 
with prehensile appendages for 
taking hold of it. The jelly- 
like Amoeba has neither mouth 
nor stomach, but extemporizes 
them, seizing its food by means 
of its soft body. The food then 
passes through the denser, outer 
portion of the body into the soft¬ 
er interior, where it is digested. 
The waste particles are passed out in a similar way. In 
the Foraminifers, thread-like projections (pseudopodia) of 
the body are thrown out which adhere to the prey. The 
soft jelly-like substance of the body then flows toward and 
collects about the food, and digests it (Fig. 15). 
A higher type is seen in Polyps and Jelly-fishes, which 
have hollow tentacles around the entrance to the stomach 
(Figs. 38 and 193). These tentacles are contractile, and 
some, moreover, are covered with an immense number of 
minute sacs, in each of which a highly elastic filament is 
coiled up spirally (lasso-cells, nettle-cells). When the ten¬ 
tacles are touched by a passing animal, they seize it, and 
at the same moment throw out their myriad filaments, 
like so many lassos, which penetrate the skin of the vic¬ 
tim, and probably also emit a fluid, which paralyzes it; the 
mouth, meanwhile, expands to an extraordinary size, and 
the creature is soon engulfed in the digestive bag. 
In the next stage, we find no tentacles, but the food is 
brought to the mouth by the flexible lobes of the body, 
commonly called “arms,” which are covered with hun¬ 
dreds of minute suckers; and if the prey, as an Oyster, is 
too large to be swallowed, the stomach protrudes, like a 
proboscis, and sucks it out of its shell. This is seen in 
the Star-fish (Fig. 126). 
