CORALS. 405 



wash over it, the polypes protrude themselves from holes 

 which were before invisible. These animals are of a great 

 variety of shapes and sizes, and in such prodigious numbers, 

 that in a short time the whole surface of the rock appears 

 to be alive and in motion. The most common form is that 

 of a star, with arms or tentacles, which are moved about 

 with a rapid motion in all directions, probably to catch 

 food. Others are so sluggish, that they may be mistaken 

 for pieces of the rock, and are generally of a dark colour. 

 When the coral is broken above high-water mark, it is a 

 solid hard stone ; but if any part of it be detached at 

 a spot where the tide reaches every day, it is found to be 

 full of polypes of different lengths and colours ; some 

 being as fine as a thread, of a bright yellow, and sometimes 

 of a blue colour. The growth of coral appears to cease 

 when no longer exposed to the washing of the sea. Thus 

 a reef rises in the form of a cauliflower, till the top has 

 gained the level of the highest tides, above which the 

 animalcules have no power to advance ; and the reef, of 

 course, no longer extends upwards." 



Of the myriads upon myriads of organised beings created 

 to work out the grand designs of Providence, all calcula- 

 tion seems futile ; as the result would be beyond the grasp 

 of our comprehension. The Polynesian Archipelago, now 

 considered to be one of the great divisions of the globe, has 

 its foundation formed of coral reefs, the spontaneous growth 

 of once-living zoophytes. Of the immense extent of the 

 geographical changes effected by the tiny polypes, Dr. 

 Man tell observes : " We may form some idea, from the 

 facts stated by competent observers, that in the Indian 

 Ocean, to the south-west of Malabar, there is a chain of 

 reefs and islets 480 geographical miles in length j on the 

 east coast of New Holland, an unbroken reef of 350 miles 

 long ; between that and New Guinea, a coral formation 

 which extends upwards of 700 miles ; and that Disappoint- 

 ment Islands and Duff's Group are connected by 600 miles 

 of coral reefs, over which the natives can travel from one 

 island to another." 



Nothing can be more impressive than the manner in 

 which these diminutive creatures carry out their stupendous 

 undertakings, which we denominate instinct, intelligence, 



