FISHERY RESOURCES OF THE PHILIPPINE ISLANDS. 305 



"The buttons after removal from the bleach liquor may be washed with water 

 containing a little hydrochloric acid. This removes the encrustation from the 

 outside and brings out the luster. After washing agiiin with water they are 

 ready for the further processes of manufacture. 



"It will be found that buttons can be bleached effectively by this means 

 and that the strength of the shell is increased by the deposition of calcium 

 oxalate in the interior.'' 



VI. PRECIOUS CORAL. 



A small spray of true precious coral {Corallium sp.) was found on the 

 beach of tlie Gulf of Davao, Mindanao, directly in front of the small 

 station called Vigas. This specimen resembled very closely a species of 

 Japanese precious coral (C. japonicum Kishinouye) . 



As it is not improbable that considerable quantities of precious coral 

 eventually may be discovered in the Islands, it seems worth while to 

 give a short description of this article of commerce, and to describe the 

 methods employed in coral fisheries. 



DESCRIPTION OF PRECIOUS CORAL. 



The precious coral of commerce in its natural state closely resembles a 

 small shrub, or the branch of a tree from w]iich the leaves have been removed. 

 Each stem and twig of this coral shrub has a hard central axis, or skeleton. 

 Outside of this and similar to the bark on a plant is the thin soft covering or 

 skin, which is easily rubbed off when fresh and is friable when dry. There are 

 numerous small holes in the "skin" through which minute, flower-like animals 

 project when the coral is alive; these are the coral animals (zooids) ; each of them 

 has 8 small arms or tentacles around its mouth, with which it gathers food. 

 All of these zooids are connected by a vascular system innide of the skin. 



The hard part or skeleton is the valuable portion of the coral. It is made up 

 of fused spicules consisting of carbonate of calcium with a small amount of silica 

 and magnesia. The structure is concentric with radiating lines. The entire 

 skeleton is very hard and so compact that no pores can be seen in a cross-section 

 without the aid of a lens. Tliis furnishes an easy test for distinguishing the 

 precious coral from the numerous varieties of no value. 



In color these corals range from white or delicate pink to dark red. Precious 

 corals reproduce sexually, and by budding. The reproductive organs are internal 

 and attached to the faces of the mesenteries; they shed their contents within the 

 body where fertilization takes place. The precious corals are believed to be 

 viviparous. Colonies are sometimes composed entirely of males, sometimes entirely 

 of females, frequently all on one branch are males, while all on another branch 

 of the same colony are females. Occasionally both se.xes are combined in one 

 animal, forming a. hermaphrodite. The eggs contain a considerable amount of 

 yolk and when hatched the larval forms are free swimming and may move a 

 fair distance before they settle and become fixed. 



The food of the precious corals consists of living organisms; they have been 

 known to eat the powdered flesh of fishes. 



VARIETIES AND DISTRIBUTION OF I^RECIOUS CORALS. 



The best known species of precious coral is C'oiaUium nolilis Pallas, more 

 generally known under its synonym of G. rubrum Linn. This species is found in 

 the Mediterranean Sea off the northern coast of Africa, also off the coast of 



