POLYPUS. 



491 



" The whole group of the thousand islands, and 

 indeed the greater part of those whose surfaces are 

 Hat in the neighbourhood of the equator, owe their 

 origin to the silent, unseen, never-ceasing labours of 

 Polypi ; their calcareous habitations are constructed 

 in an infinite variety of forms, yet with that order 

 and regularity, each after its own kind, that is so dis- 

 cernible to the minute inquirer in every part of 

 creation. It is true the eye may easily be convinced 

 of the fact ; but it is difficult for the human mind to 

 conceive the possibility of animals, so apparently in- 

 significant, being endowed with the power, much less 

 of being furnished in their own bodies with the mate- 

 rials of building up the immense fabrics which, in 

 almost every part of the Eastern and Pacific Oceans 

 lying between the tropics, are met with in the shape 

 of detached rocks, or reefs of great extent, just even 

 with the surface of islands already clothed with 

 plant?, whose roots are fixed at the bottom of the sea 

 several hundred feet in depth, where light and heat 

 so very essential to animal life, if not excluded, are 

 sparingly received and feebly felt. 



" Thousands of such rocks, reefs, and islands, are 

 known to exist in the Eastern Ocean, within and even 

 beyond the limits of the tropics. The eastern coast 

 of New Holland is almost wholly girt with reefs and 

 islands of coral rocks rising perpendicularly from the 

 bottom of the abyss. Captain Kent, of the Buffalo, 

 speaking of a coral rock many miles in extent, on the 

 south-west coast of New Caledonia, observes, that it 

 \ level with the water's edge, and towards the sea as 

 steep as the wall of a house ; that he sounded fre- 

 quently within twice the ship's length with a line 

 150 fathoms (900 feet), without being able to reach 

 the bottom. 



That delightful writer and intelligent traveller, 

 Captain Basil Hall, in his voyage to the Loo Choo 

 Islands, has also made some intonating remarks on 

 the examination of a coral reef; he observes that 

 during the different stages of one tide the changes it 

 undergoes is truly surprising. When the tide has 

 left it for some lime it becomes dry, and appears to 

 be a compact rock, exceedingly hard and ragged ; but 

 as the tide rises, and the waves begin to wash over 

 it, the coral worms protrude themselves from holes 

 which before were invisible. These animals, he says, 

 are of a great variety of shapes and size, 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 wonn is in the form of a star, 

 with arms from four to six inches long, which 

 are moved about in all directions, probably to catch 

 food. Others are so sluggish that they may be mis- 

 taken for pieces of rock, and are generally of a dark 

 colour, from four to five inches long and two or three 

 round. When the coral is broken about 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 worms of different lengths and 

 colours, some being as fine as a thread and several 

 foot long, of a bright yellow, and some of a blue 

 colour ; others resemble snails, and some are not 

 unlike lobsters in shape, but soil, and not above two 

 inches long. 



The growth of coral appears to cease when the 

 worm is no longer exposed to the washing of the sea. 

 Thus a reef rises in the form of a cauliflower, till its 

 top has gained the level of the highest tides, above 

 which the animal has no power to advance, and the 



reef, of course, no longer extends itself upwards ; the 

 other parts, in succession, reach the surface, and 

 there stop, forming in time a level field, with steep 

 sides all round. The reef, however, continually in- 

 creases, and, being prevented from growing higher, 

 extends itself laterally in all directions ; but, the 

 growth being as rapid at the upper edge as it is 

 lower down, the steepness of the face of the rock is 

 still preserved. These are the circumstances which 

 render coral reefs so dangerous to navigation ; for, 

 in the first place, they are seldom seen above the 

 water ; and, in the next, their sides are so perpen- 

 dicular that a ship's bow may strike against the rock 

 before any change of soundings has given warning of 

 the danger. 



To the remarks of these travellers we will add 

 those of another, an accurate observer of nature, 

 whose frequent visits to the coast of New Holland 

 fully confirm these accounts. His diffidence has 

 hitherto prevented the public from enjoying the ani- 

 mated description he gives of the wonderful pheno- 

 mena coral formations exhibit. We have, neverthe- 

 less, his permission to extract an observation from 

 his manuscripts, which does not appear to have been 

 made by any other naturalist or traveller with whom 

 we are acquainted, or whose publications have ap- 

 peared. It is the magic effect produced by the 

 almost instant growth of vegetable matter on these 

 rocks ; for, no sooner have the Polypi become 

 checked in the upward progress of their eternal 

 labour, by having reached the level of the sea, and 

 are forced to work their restless course beneath its 

 surface, than the upper world, jealous, as it were, of 

 territory thus forced upon it, immediately claims it, 

 and peoples it anew. It is rapidly clothed with 

 verdure ; an artificial soil is quickly deposited by the 

 exuviae of marine animals and plants. The excrement 

 of birds, who flock in countless myriads to feast upon 

 the sea's rejectamenta, greatly assists to increase the 

 stratum of soil, leaving with it the seeds of plants and 

 trees, that, springing into life, quickly attain maturity 

 in such congenial ground, and, in their turn, contribute 

 largely to their parent soil, as the succeeding changes 

 of season, with unerring truth, divrst them of their 

 leafy garb. By these causes repeated strata of earthy 

 matter are deposited ; a verdant island rises, smiling 

 in the face of desolation, and bids defiance to the 

 angry storm, forming possibly a future asylum to 

 man, or the subject of a state's contention. 



Another fact, less easily accounted for, but proving 

 the infinite goodness of God, is, that on these islands 

 fresh water is almost always to be found in the 

 hollow bvisins below the level of the sea, and in the 

 cavities formed in the earthy cavities on the face of 

 the island, and generally in the most open situations. 

 May not this be caused (without any very extrava- 

 gant stretch of hypothesis) by the immense pressure 

 of the surrounding medium forcing the wafer through 

 the rocky interstices, and filling these basins by a 

 species of infiltration, during which much of its saline 

 particles are purged, and it is ultimately purified by 

 the heat of the sokir rays, which crystallise tho 

 remaining salt, and precipitate it to the bottom of 

 these gigantic evaporating basins, immediately sup- 

 plying vegetation and animal life with their most 

 necessary and salutary aliment, water, in addition to 

 that which the bounteous streams of heaven season- 

 ably supply ? 



Montgomery, in his poem " The Pelican Island," 



