458 NATURAL SCIENCE. June. 



The pearl and pearl-shell fisheries are of great importance. As 

 an export from Queensland, pearl shell has ranked for the last five or 

 six years as the sixth or eighth most important substance. These 

 fisheries are confined to the tropical area of the Queensland coast, and 

 are intimately associated with the Barrier-reef. The mother-of-pearl 

 shell is collected in water from 7 to 20 fathoms deep. Formerly it 

 was found in areas practically exposed at low tides. Queensland 

 derives a revenue from licenses required to be taken by boats, 

 ships, and sailing masters, and from a small royalty on the amount 

 of shell collected. 



Owing to considerable depletion of the more readily accessible 

 fishing grounds, the average weight of shells has decreased. Large 

 shells weighing six to eight pounds a pair are still to be got, but the 

 more ordinary yield averages two-and-a-half pounds the pair. A 

 protecting Act of Parliament now prohibits the taking of shell with a 

 less diameter than six inches across the pearl lining or " nacre." 



The specific form of the Queensland waters is Meleagrina 

 margaretifera. Actual pearls of large size and fine quality are found, 

 but enormous numbers of the shells contain worthless forms. 



Some experiments have been made in the artificial production of 

 pearls, not according to the Chinese methods by introducing metallic 

 or other foreign bodies into the mouth to be covered by a pearly coat, 

 but the process has as yet only a speculative value. 



The author made a series of experiments with a view of finding 

 methods of removing young shells from the breeding grounds to 

 shallow water where they might grow to maturity in undisturbed 

 security. He found that young living examples with a diameter of 

 no more than a quarter of an inch might be safely removed by cutting 

 through the byssus. When the animal was placed in an aquarium 

 the remains of the byssus were ejected and a new byssus secreted, 

 and in most cases a secure reattachment formed in the new habitat. 

 The animals have a slight power of locomotion, but nothing com- 

 parable with the active movements of pectens. 



In removing larger shells from deep water for relaying in shallow 

 water, several methods were tried. Some were placed in shady places 

 on deck and had sea-water thrown over them at intervals. For 

 others, the American method (employed in the case of oysters) — 

 muzzling the shells with wire to prevent the opening of the valves — 

 failed to secure the retention of the fluids in the shell, as they escaped 

 by the byssus groove. The mortality in these two cases was very 

 great, but entirely successful results were obtained when the shells 

 were kept in tubs of water, the water of which was changed every 

 few hours, and the actual shells immersed in basket-work frames in 

 the sea at night. 



When these shells were laid down in frames in shallow water 

 where the water was pure and the currents strong, remarkably 

 healthy and active growth took place. It may indeed be said that 



