The Best Pearl is the Tomb of a Worm.

Kaipara and Waitemata Echo, 16 October 1914, Page 2

The Best Pearl is the Tomb of a Worm.

The oyster makes a pearl to get rid of the annoyance of an enemy, generally a worm, that sneaks inside his shell. But in doing this he comes nearer ' being "hoist by his own petard" than any other thing known iii the lower order of life. While he gets ■ rid of the troublesoineWorin or other foreign, matter !>y making a pearl around it, he makes himself so much more valuable to man by this process that his life is in ten times the danger it was from the object that caused his first annoyance. Sometimes a pearl is the result of a /grain of snnd getting inside the shell which the bivalve is unable to dislodge. Rut recent investigations have shown that the pearls resulting from a grain of sand are by no means as valuable as those resulting from worms. And so it is that the rc-aJly valuable pearls are nothing more or less than tombs for cestode or trenuntode worms. It is the cestode worm that seems to be responsible for the best grade of

pearls, with the trcmatode worms for the second grades. The manner in which the oyster makes the pearl is extremely simple. Every step of the process has now been learned by naturalists. In the first place the foreign matter, generally a worm, works itself inside the shell of the oyster. The oyster is unable to get rid of it, and it continues to annoy him. Now the back line (A) represents the outer shell of the oyster, with the lime next to that. (B) is the worm or other foreign matter. When the oyster finds he cannot dislodge the worm he begins to deposit a layer of mother-of-pearl (C) aroun.i it. The oyster is constantly buil :- ing his shell by this means. When the foreign matter is covered with sufficient mother-of-pearl the oyster stretches his outer skin (D) untii the edges .meet where they grow together and detach that portion en- ] circling the mother-of-pearl-covere:l worm. In time the deposits begin to increase until the layer after layer of iridescent mother-of-pearl has formed the >.i.;r.ual valuable pearl. The outer skin now wears away or dissolves and leaves the smooth round pearl. In fact, it leaves the worm so entombed that it is perfectly harmless. To be exact, a pearl is merely a lump of carbonate of lime mixed with organic matter, which shows its wonderful colours only because of its layer after layer of the ] mother-of-pearl structure. Pearls are found in various bivalves, although the oysters furnish most and generally the best. Sometimes the colour of the pearl depends upon the feeding beds which .determine the tints of the lime from which the oyster makes its shell This gives rose pearls or browta or s< -called black pearls. And so the beautiful wmian wnose throat is adorned with a stvin::; ■■.■: rare and almost priceless pearls is really wearing a string of insectcoflins around her neck. Sometimes the oyster can cover the worm or grain of sand with mother-of-pearl and entomb it against the inner side of the shell, leaving a little knot or protuberance of real pearl. These are cut out for scarf-pins and buckles and are known to the trade as "half pearls." But they are, like the round pearls, the tomb of some unfortunate worm that dared venture inside the oyster's shell castle.