THE LITHOPHYTES AND SPONGES. 



571 



endued with a vegetation entirely resembling 

 that which is found upon land. This opinion, 

 however, some time after, began to be shaken 

 by Rumphius and Jussieu, and at last by the 

 ingenious Mr Ellis, who, by a more sagacious 

 and diligent inquiry into nature, put it past 

 doubt, that corals and sponges were entirely 

 the works of animals, and that, like the honey- 

 comb which was formed by the bee, the coral 

 was the work of an infinite number of reptiles 

 of the polypus kind, whose united labours 

 were thus capable of filling whole tracts of the 

 ocean with those embarrassing tokens of their 

 industry. 1 



1 Coral. The method in which the polypus secretes 

 the coral, which, when taken from the sea, is in stalks 

 about a foot high and half an inch thick, is understood 

 to be as follows : An egg or new animal, when ejected, 

 falls upon some body, to which, from its gelatinous na- 

 ture, it adheres. On this foundation it spreads and 

 moulds itself, till at length from the middle of it a sort 

 of excrescence rises upwards, containing the germ of 

 a new animal, which attains its growth by degrees, 

 and sends up a similar extension. These deposite cal- 

 careous or chalky matter in the middle, and by the con- 

 stant generation of new polypi, and the secretion of ad- 

 ditional matter, the coral, at the end of ten years, which 

 is the period necessary for its perfect growth, has at- 

 tained the height and thickness mentioned. It is of 

 various colours red, vermilion, and white, the latter 

 being most common, and consequently least valuable. 

 When taken out of the sea, it is covered with moss and 

 marine vegetable matter, and is generally somewhat 

 softer and duller in hue than it ultimately becomes. 



The coral fisheries form a very considerable trade in 

 several parts of the Mediterranean. From the hollows 

 and caverns of the rocks, where it takes root, the coral 

 is brought up with nets ; it also grows, but in less quan- 

 tities, on the sides of the ocean crags. The greatest 

 height to which it attains is never above a foot, and its 

 usual thickness is about that of the little finger, though 

 often much less. The most extensive fisheries are those 

 carried on in the straits of Messina, off the Sicilian coast, 

 and about three miles distant generally from the land. 

 The fishermen have divided the whole tract, about six 

 miles in length, into ten parts. Every year they fish 

 only in one of these parts, and do not interfere with it 

 again till ten years have elapsed, for the purpose of 

 bringing away only such coral as has attained its full 

 growth. 



The appearance of the coral as it is observed in the 

 sea, is said to resemble a miniature forest, from its great 

 quantity and branching character. The greatest portion 

 is procured from a depth of from sixty to a hundred and 

 twenty-five feet ; but some fisheries are carried on to 

 the depth of nine hundred feet. Those of the coasts of 

 Marseilles, Barbary, and Trapani, are the principal 

 rivals to the Sicilian fisheries in the European market, 

 but none of them produce the coral in equal quantities, 

 or of equal quality, with the latter. From Messina 3000 

 pounds are said to be exported annually ; the price of 

 which is so much affected by the colour and quality, that, 

 while some of it is valued at ten guineas a pound, other 

 portions are considered not worth ten pence. The ver- 

 milion-coloured coral, being the rarest, is the most ex- 

 pensive. The common red, however, brings a high 



rice also, when the quality is good. Chemical analysis 

 proved that the coral consists of carbonate of lime, a 

 cies of chalk, for it dissolves completely in aquafortis, 

 or nitric acid. 



Though we may regard with some degree of wonder 



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1 



If, in our researches after the nature of 

 these plants, we should be induced to break 

 off a branch of the coraline substance, and 

 observe it carefully, we shall perceive its 



the production of stalks of coral by a small oyster-like 

 polypus, our astonishment cannot fail to be increased 

 when we consider, that, by an animal of the same size 

 and species as the coraliferous polypus, whole reefs of 

 great extent, and even islands, have been founded and 

 originated. The animal or polypus that accomplishes 

 this is called the Madrepore, and has long been errone- 

 ously considered as identical with the coral polypus ; 

 hence the masses of land alluded to have received the 

 appellation of coral reefs and islands. These have never 

 yet been found in any extent excepting in the Pacific and 

 Asiatic seas, but in these immense waters the coral rocks 

 and reefs are abundant. 



The principal groups of islands of coral formation are, 

 from the New Hebrides, eastward, the Friendly islands, 

 Navigation islands, and the Society islands ; and, to 

 the northward of the latter group, the Marquesas. These 

 groups are separated from each other by channels or seas, 

 wider than those which separate the individual islands 

 which form the respective groups; but all these waters 

 abound with shoals and minor islets, which indicate the 

 existence of a common base, and show that the processes 

 by which they will hereafter be united above the level of 

 the sea, are in constant operation. 



The structure and progress of these islands towards a 

 state of fitness for the habitation of man, has been thus 

 described. At a vast but unknown depth, below the 

 surface of the sea, the insects attach themselves to the 

 upper points and ridges of rocks, which form the bottom 

 of the ocean, and many of which, in the Pacific ocean, 

 are supposed to be of volcanic origin. Upon these foun- 

 dations, the little architects labour, building up by means 

 of the secretion before described, pile upon pile of their 

 rocky habitations, until at length the work rises above 

 the sea, and is continued to such a height, as to leave it 

 almost dry at low water, when the insect leaves ofi'build- 

 ing upon that part. A solid rocky base being thus formed, 

 sea-shells, fragments of coral, and sea-sand, thrown up by 

 each returning tide, and broken and mixed together, by 

 the action of the waves, become in time converted into 

 a sort of stone, and thus raise up the surface higher and 

 higher. The heat of the sun so penetrates this mass of 

 stone, that it brakes off into flakes, and these flakes are 

 again raised one upon another by the waves, at high 

 water. The. ever active surf continues to throw up the 

 shells of marine animals, and other materials, which fill 

 up the crevices between the stones, and the sand upon 

 the surface being now undisturbed, offers to the seeds of 

 trees and plants cast upon it by the waves, a soil upon 

 which they rapidly grow, and over-shadow the dazzling 

 whiteness of the new formed lands. Trunks of trees, 

 washed into the sea by the rivers from other countries 

 and islands, find here a resting place, and with these 

 come some small animals, chiefly of the lizard and insect 

 tribes. Even before the trees form a wood, the sea-birds 

 nestle among them, and soon the stray land-bird takes 

 refuge in the bushes. At a latter period, man appears, 

 builds his hut upon the fruitful soil formed by the cor- 

 ruption of the vegetation, and calls himself lord and pro- 

 prietor of this new creation. 



These islands vary in extent, as well as in the degree 

 of finish to which they have arrived. Of thirty-two ex- 

 amined by captain Beechey, the largest was thirty miles 

 in diameter, and the smallest somewhat less than a mile. 

 They were of various shapes, and all formed of living 

 coral, except one, called Henderson's island, which was 

 partially surrounded by it ; and they all appeared to be 

 increasing in size by the active operations of the zoo- 

 phytes, which are gradually extending, and building up 



