490 



POLYPUS. 



live through centuries, setting the tooth of time at 

 defiance. Some of the Polypidoms have only this 

 ephemeral life ; the existence of others seems oternal 

 and coeval with the world's formation ; this ob- 

 servation does not, however, apply to the Polypi, 

 as they, separately considered, do not appear to 

 possess a long life, but, on the contrary, many cir- 

 cumstances induce us to believe it of a very limited 

 duration. 



In the Fhistra, Cellularia, and Sertularia, annual 

 species are found, and others are subordinate to the 

 marine plants that support them. In almost all Po- 

 lypidoms the lower parts are wholly devoid of ani- 

 malculae, and in the greater number they are only 

 seen at the extremities. Some there are entirely 

 covered with animated Polypi through the summer 

 and autumn, but they then decline, and finally perish 

 with the cold of winter. No sooner, however, has 

 the sun resumed his revivifying influence, than new 

 animals are developed, and fresh branches are pro- 

 duced upon the old ones. The lower portion appears 

 inert, and deprived of all kind of life ; the Fhistra, 

 Sertularia, and Gorgonia, afford many examples of 

 this. Arrived at the last stage of existence, the 

 Polypidom languishes ; it has no longer the power to 

 resist the destructive influence of time, or the attack 

 of those natural enemies which the energies of life 

 till then repulsed. Some of these feed on its fleshy 

 envelope ; others penetrate to the interior of the axis, 

 and live on its substance, however solid it may be, or, 

 by perforating it in various directions, destroy its 

 support, sending it a wreck to the mercy of the 

 waters, till at last the fragments perish, and are cast 

 upon the shore in a form scarcely recognisable, being 

 reduced to grains of calcareous sand, again destined 

 to become incorporated and rendered subservient to 

 man's use in some other shape. 



In the vegetable world plants are found in all lati- 

 tudes, in all climates, in every soil, whether on the 

 roof of the peasant's cottage, or on the marble dome 

 of a palace : the number of such is, however, incon- 

 siderable ; but the majority of vegetables that adorn 

 the surface of the globe require a particular soil and 

 climate. This, however, is not the case with Polypi- 

 doms ; few of them prefer one substance to another as 

 a point of attachment ; the greater proportion of these 

 creatures, requiring only one fixed point of rest, attach 

 themselves indifferently to any hard or solid body the 

 sea presents ; they are seen on primitive, secondary, 

 and other rocks, sometimes on stems of marine plants, 

 on blocks of lava, fragments of vases, or other anti- 

 quities, and even on human skulls. Sometimes these 

 Polypidoms wholly envelop fragments of wood that 

 float on the surface of the water ; at other times they 

 surround and bury the wrecks of old vessels aban- 

 doned in ports and other places ; and there are some 

 whose base dividing into numerous fibres, like the 

 root of a tree, penetrate deeply into sandy or muddy 

 shores to find a point of fixation which the surface 

 cannot afford them. In general their base is solid 

 or extended in the corticiterous Polypidoms, fibrous 

 in the calciferous, and non-existing, or nearly so, in 

 the carnoid and celluliferous classes ; thus, as this 

 part only serves the Polypidom as an anchor, we may 

 consider it as a means employed by nature to prevent 

 those beings, deprived of locomotive power, from be- 

 coming the sport of the waves. In this respect only, 

 independent of their external configuration, do they 

 resemble vegetable production!. The forms of Poly- 



pidoms are too various to admit of a general descrip- 

 tion, as the following outline will exhibit. 



The celluliferous appear aggregations of isolated 

 cells, placed on the surface of marine bodies, or else 

 cells so united as to form by their adhesion to each 

 other a thin crust on the surface of the thalassiophites 

 or testaceous molluscs, and frequently appear in 

 leafy diversified expansions ; sometimes these cells 

 are placed on stems like leaves on their branches ; in 

 others they appear in the form of very long branching 

 or simple tubes, separated from each other in their 

 upper part, and united in their lower, to form stems, 

 as well as a firm foot or root, by which they adhere 

 to some solid immovable base. 



In the calcifero'is there also exist great disparities ; 

 some of them ramify like shrubs, whilst others divide 

 in numberless dichotoma, or resemble a paintei's 

 brush ; some take the form of an umbrella or an open 

 fan ; some are simple, others branched ; some arti- 

 culated, others compressed ; some flat, and others 

 cylindrical. 



The corticiferous display an equal variety ; there are 

 spongia that spread in thin patches on the rocks and 

 marine plants ; others form themselves into globular 

 masses, or are hollowed in the form of tunnels ; many 

 rise in tubes like organ-pipes, and some divide in the 

 form of thick leaves. What an infinite variety of 

 form exists between the Gorgonin with its simple 

 unbranched stem, and others whose anastomosed 

 branches resemble the reticulations of net-work, or as 

 in the flabellated andyomena, in which they are so 

 regularly and elegantly designed, that they resemble 

 delicately worked lace. 



The isidia has an alternately stony and cartila- 

 ginous stem, bearing some resemblance to the ver- 

 tebra of an animal of more perfect organisation ; others 

 in appearance may be compared to shrubs despoiled 

 of their leaves, but covered with flowers, whose snowy 

 whiteness is heightened by being contrasted with the 

 deep and brilliant red of the branches. 



In the earnoid Polypidoms differences almost as 

 numerous exist, but they are much less known than 

 those described in the preceding orders. 



Having thus briefly given a general idea of the 

 form of Polypidoms, a more general description will 

 scarcely be expected ; for, if this be impracticable in 

 one division, it must remain so with regard to all 

 other of these animal architects. 



With respect to the size of Polypidoms, we find 

 some so minute, that it requires the aid of glasses to 

 discover them, whilst others are as elevated as the 

 mountains, their heads raised to midway air, their 

 base fixed in the sea's foundation to a depth unfa- 

 thomable ; such are the madreporouj islands so 

 numerous in the south-eastern ocean, where they are 

 hourly augmenting by the incessant and inconceivable 

 labours of countless myriads of Polypi. Some geo- 

 logists have imagined that these isles were only the 

 summits of submarine mountains that had been co- 

 vered, or, as it were, encased by Pob/pidoms; but 

 submarine mountains, the almost perpetual source of 

 subterranean fires, are found in all latitudes, and 

 greatly vary in their extent and in their forms. The 

 madreporean islands, on the contrary, exist only 

 within the tropics, and present forms constantly ana- 

 logous to each other, nor are they ever overturned 

 by earthquakes or volcanic eruptions. These are 

 described in the following extracts by veracious tra- 

 vellers who have traversed those seas. 



