CORAL 601 



CORAL. 



Red or precious coral is a material almost as imjjortant for decorative and oraamental 

 purposes as are precious stones and pearls. It constitutes the substance of the calcareous 

 axial skeleton of the coral polyp, Corallmm rubrum, a lowly organised animal belonging to 

 the class Anthozoa. The Mediterranean Sea is the principal habitat of this coral ; and not 

 only is it fished almost exclusively by Italians, but the working of the rough material is for 

 the most part in the hands of the same people, so that we are dealing with what is 

 practically an Italian industry. 



Corallium rubrum has been sometimes known by other names, such as CoralUum nobile, 



Isis nobilis, &c., but these terms are no longer employed. This coral is not a solitar\- 



organism, but forms branching colonies. Each colony is supported by an axial rod of red 



calcareous material, the so-called coral, and this is invested by a layer of soft, living 



material known to zoologists as the coenosarc. At intervals along the branches are situated 



the individual polyps, embedded, as it were, in the coenosarc, with the material of which 



\ their bodies are continuous. The cells of the coenosarc have the power of separating out 



\ calcium carbonate from the sea water, in which the coral lives, and this forms the substance 



iof the axial skeleton of the colony. From this the ccenosarc can be peeled off " like the 



Ibark of a willow twig in spring," leaving it a clean, red, branching rod, the coral of 



<;onimerce. It is proposed, first, to consider th-i structure and life-history of a colony of 



€oraMium rubnim in some detail, and afterwards the methods employed for collecting coral 



■apd its manufacture into ornamental articles. 



I The Coral Skeleton. — The calcareous skeleton of a colony of Coralliurn rubrum is 

 rell — more rarely white or black — in colour and arborescent in form. It is attached firmly by 

 a Idisc-shaped foot to any suitable object in the sea, such as a rock or a large stone. 

 Collonies have also been found fixed to cannon-balls, bottles, shells, or other corals, and in 

 one case a human skull. The disc-like foot affords a firm base for the whole structure. It 

 canliot penetrate the rock or other object to which it is attached as do the rootlets of a 

 plant, but any depressions, furrows, or cracks in the surface are filled up with calcareous 

 material, which thus cements, as it were, the two together. The main axis and its lateral 

 Ijranches are not straight, but curved, like the trunk and branches of a tree or shrub. The 

 former seldom exceeds a foot in length and an inch in diameter. From a single disc-like 

 foot there may grow out, not one, but several independent colonies, which are then usual! \- 

 of small size. This is especially the case with the corals off the coast of Provence. 



The growth of a coral-colony is not affected by gravity in the same way as is that of 

 plants ; it always grows in a direction perpendicular to the surface to which it is attached, 

 regardless of its inclination to. the vertical. If attached to some object on the bottom of 

 the sea, its direction of growth will be vertical and upwards ; if to the vertical face of a 

 rock it will grow out in a horizontial direction ; and when attached to the roof of a x'ock 

 cavity, it grows vertically downwards, this being, indeed, a direction commonly taken. 



The main axis of the skeleton tapers gradually to a blunt point, so gradually, indeed, 

 that a short length of it may appear perfectly cylindrical. It may commence to branch 



