CURIOUS WAYS OF GETTING FOOD. 773 



in the water. In that immense aggregation of minute animals, the 

 sponge, the canals ramifying through the mass are lined with cilia, 

 which cause constant currents of water to pass in at the small pores 

 and issue at the large openings. Thus " the sponge represents a kind 

 of subaqueous city, where the people are arranged about the streets 

 a^id roads in such a manner that each can easily appropriate his food 

 from the water as it jaasses along." Cilia fringe the gills of the bivalve 

 mollusks, like the oyster and scallop, or the clam, which can burrow in 

 the sand and send up into the water a long tube or siphon. 



The great Greenland whale subsists on the small animals which 

 swarm in the Arctic seas. But how shall the enormous beast capture 

 sufficient of those tiny creatures ? Its apj^aratus is as remarkable as it 

 is unique — a huge sieve, made of the fringed edges of hundreds of 

 " whalebone " plates, hanging from the roof of the mouth. Filling 

 its cavern-like mouth with water containing the small animals, these 

 are strained out as the water is expelled. 



Solid food in mass requires some means of grasping — true prehen- 

 sion ; generally accompanied by the power of dividing or crushing — 

 mastication. A most curious method, and but one step higher than 

 shown in the tapeworm, is exhibited by the microscopic amoeba, found 

 in fresh water. An animal without any permanent appendages what- 

 ever, a bit of almost structureless protoplasm, it nevertheless moves 

 without limbs, breathes without gills, seizes food without prehensile 

 organs, and digests without a stomach. All the animal functions are 

 performed by the general mass of the body. Its mode of feeling is as 

 follows : When a nutritious particle comes in contact with the body, 

 the surface at that point begins to depress or fall in, and so continues 

 until the surrounding surfaces meet and unite. In other words, the 

 animal wraps itself around the particle, and the bit of food is enveloped 

 in the albuminous body-mass. The nutritive matter is absorbed, and 

 any undigested or waste matter is expelled by a reverse process. 

 Briefly, the amoeba extemporizes a stomach upon the place and at the 

 time it is needed, and is not troubled with that uneasy organ when it 

 is not needed. The ills of dyspepsia are to the amoeba unknown. 



The polyp or sea-anemone has numerous grasping arms called ten- 

 tacles surrounding the mouth, which is at the top of the stump-shaped 

 body. But the muscular power of the soft, watery animal is not suf- 

 ficient to hold a lively crab or other struggling prey. To supplement 

 this weakness, it is provided with a most marvelous and deadly appa- 

 ratus. The surfaces of the tentacles, and frequently of the stomach 

 and body-walls, hold countless minute sacs containing beautifully coiled 

 filaments, which are quickly thrown out like so many poisoned darts 

 to pierce and paralyze the victim. The structure and action of these 

 stinging threads is one of the greatest wonders of nature. The weak 

 jelly-fish uses the same means to overpower its prey, which, enveloped 

 and paralyzed by the hundreds of thread-like tentacles, is drawn up- 



