686 THE POPULAR SCIENCE MONTHLY. 



branches of the coral, we behold animated life ; a world in itself is 

 spread before us ; here dwell most of the various inhabitants of the 

 sea — snails, shells, and sea-urchins, fishes and crabs of the queerest 

 shapes. Here in the domain of color, where everything seems brill- 

 iantly attired, they are less easily discovered by their enemies than in 

 the ocean. In fact, one can often observe that the exterior of animals 

 is in accordance with their surroundings. The inhabitants of the 

 desert have a sand-like color ; those of the polar regions are of light 

 shade ; some caterpillars resemble the twig of a tree ; some butterflies 

 look like dried leaves ; and a grasshopper has, on account of the shape 

 of its body, received the name of " wandering leaf." 



But the beautiful aspect presented by a branch of coral, when un- 

 der water, immediately vanishes when it is removed from its native 

 element, as the many little arms are then contracted. The skeletons 

 of various species are, however, much sought for as ornaments, above 

 all the black coral of India, which is considered a talisman. Next in 

 value ranks the red coral, found near Algiers, and third in rank comes 

 the white. 



Another kind of plant-animals, which build structures like those of 

 the coral, only not so large, not so hard, nor so lasting, are the sponges, 

 sea-animals in the strictest sense of the term. The eastern part of the 

 Mediterranean, and the Red Sea particularly, abound in valuable 

 sponge-beds, on rocky soil. Numerous vessels arrive there every sum- 

 mer to collect the crop. Recently the cultivation of artificial sponge- 

 plantations has been tried by taking a piece of fresh sponge, which 

 still contained the slimy bodies of the sponge-animals, and planting the 

 same in a favorable spot. The experiment succeeded admirably. 



It seems easy and natural enough to turn our attention from the 

 sponges to chalk. This very important writing -material is, as is well 

 known, an accumulation of minute animal remains, or, more correctly 

 speaking, of their calcareous shells. What large deposits they are 

 capable of forming is shown by the chalk-cliffs of Riigen, by those of 

 Great Britain, to which the island owes the name of "Albion" (white), 

 and by those of Crete, from which the German word " Kreide " (chalk) 

 is derived. 



The chalk-cliffs arose from the ocean, but their later upheaval is 

 due to volcanic eruption. The minute animals, which form the masses 

 of chalk, are of various shapes ; some resemble the houses of snails, 

 some the cone of a pine, others again are staff-like. 



The largest of the existing three hundred kinds have been known 

 since the oldest of times, for they were found in the stones used by 

 the builders of the Pyramids. Their incasement is greatly perforated, 

 and from their pores they send forth numerous fine, slimy feet, which 

 constantly fluctuate to and fro. By adhering closely to one another 

 they cover their food-supply, and then gradually assimilate the same. 



As the aurora borealis flashes through the darkness of the polar 



