98 STUDIES IN INSECT LIFE, ETC. 

 or stone dropped by a passing iceberg, or a piece 

 of pumice thrown out by some volcano, which 

 after floating about on the surface for a time has 

 become water-logged and dropped to the bottom ; 

 or, again, the wreckage of men's ships : 



" The wrecks dissolve above us : their dust drops down from 



afar 



Down to the dark, to the utter dark, where the blind white 

 sea-snakes are," 



or the bones and skeletons of whales and fishes 

 and sea-birds lie awaiting burial by the ceaselessly 

 falling Foraminifera. For if we examine a speci- 

 men of the ooze just described we shall find it 

 consists of countless millions of small, microscopic, 

 chalky shells, the innumerable homes of un- 

 numbered unicellular animals, which, when alive, 

 floated on the surface of the ocean. 



The great mass of these belong to the group of 

 Foraminifera, microscopic animals which have 

 the power of secreting calcium carbonate from the 

 sea-water and building it up into shells of many 

 chambers. These shells compacted together form 

 the white cliffs of our coasts and the chalk downs 

 of our southern coasts. Foraminifera are capable 

 of extraordinarily rapid reproduction, and at times 

 the surface of the sea is almost packed with them. 



