Feb. 1, 1865.] THE TECHNOLOGIST. 



THE TINNEVELLY PEARL-BANKS. 301 



main on the layings there is danger of the oysters being choked with 

 mud. The oysters remain on the layings for two years, when they 

 are fit for eating, and during this time there are constant examinations 

 in order that all dead fish may be removed, and the cultch kept clear of 

 mud. In places where the layings are never laid bare by the tide, this 

 is done by means of a dredge, all live fish and cultch being carefully 

 thrown back, while dead fish, soft mud, and mussels are removed. 



There can be little doubt that some such system might be adopted 

 in rearing pearl oysters ; and Dr. Kelaart says that " he sees no reason 

 why pearl oysters should not live and breed in artificial beds, like the 

 edible oysters, and yield a large revenue." He has ascertained, by his 

 experiments in Ceylon, that the pearl oysters are more tenacious of life 

 than any other bivalve with which he is acquainted, and that they can 

 live in brackish water, and in places so shallow that they must be 

 exposed for two or three hours daily to the sun and other atmospheric 

 influences. Captain Phipps, the superintendent of tne Tinnevelly 

 pearl-banks, has come to the same conclusions; and, convinced that 

 artificial nurseries for the young oysters are the only means by which 

 remunerative fisheries can be insured, he has proposed the following 

 plan, which has been adopted : — 



The harbour of Tuticorin is formed by two long islands, and between 

 them and the mainland there is a bank about three miles long by a 

 quarter of a mile broad, with a depth of from three to seven feet, 

 entirely free both from surf, currents, and influxes of fresh water. 

 Captain Phipps proposes that this bank should be walled round with 

 loose coral until it is formed into a basin, the edges rising three feet 

 above high-water mark. Over the bed of the shallow basin thus 

 enclosed, live coral will be regularly spread, so as in a few years to form 

 a solid mass, serving the purpose of cultch, and the basin will be divided 

 into three parts, one for the old oysters, and the other two for the young 

 ones that may be in process of rearing. After the division of the basin 

 set apart for breeding has been stocked, it will be carefully watched, 

 and when the spawning has taken place and the young oysters are well 

 formed, they will be removed from the old oysters and rocks to which 

 they are attached, and placed in one of the separated parts of the basin, 

 and the same plan will be followed each succeeding year. On reaching 

 a sufficient age, they will again be removed to one of the pearl-banks 

 in the open sea. The last operation is necessary, because it would be 

 impossible to enclose an artificial space which would hold as many 

 grown oysters as are required for a remunerative fishery, and because it 

 is believed that the quality of the pearl depends on the depth and clear- 

 ness of the sea in which it has been formed. 



A single oyster, five or six years old, often contains no less than 

 12,000,000 eggs, and in the fishery of 1861 the total number taken only 

 amounted to 15,874,500, so that the number of young ones annually ob- 

 tained from the nursery will be abundantly sufficient to stock banks for 



