THE PEARL FTSITERIES (^F CEYLON. 489 



safer locality further inshore. jNIr. Hornell was authorized hv the 

 governor of Ceylon to carry out this reconnnendation, and went to the 

 Periya Paar early in Novemljer with hoais and ai)pliances suitable 

 for the work, but found he had ai'rixcd too late The soutlnvest mon- 

 soon had intervened, the bed had apparently been swejit clean, and 

 the enormous population of youno- oysters, which we had seen in 

 March, and which might have been used to stock many of the smaller 

 inshore paars, was now in all probability either l)uried in sand or car- 

 ried down the steep declivity into the deej) watei- outside. This expe- 

 rience, taken along with what we know of the })ast history of the bank 

 as revealed by the inspectors"' reports, shows that whenever young 

 oysters are found on the Periya Paar they ought, without delay, to l)e 

 dredged up in bulk and transplanted to suitable ground in the Cheval 

 district — the region where the most reliable paars are ])laced. 



From this example of the Periya Paar it is clear that in considering 

 the vicissitudes of the pearl oyster banks we have to deal with great 

 natural causes Avhich can not be removed, but which may to some 

 extent be avoided, and that consequently it is necessary to introduce 

 large measures of cultivation and regulation in order to increase the 

 adult population on the grounds, give greater constancy to the sup- 

 ply, and remove the disappointing fluctuations in the fishery. 



There are in addition, however, various minor causes of failure of 

 the fislieries, some of which we are able to investigate. The pearl 

 oyster has many enemies, such as star-fishes, boring sponges which 

 destroy the shell, boring moUusks which suck out the animal, internal 

 Protozoan and Vermean parasites and carnivorous fishes, all of which 

 cause some destruction and wdiich may consjiire on occasions to ruin 

 a bed and change the prospects of a fishery. But in connection with 

 such zoological enemies it is necessary to bear in mind that from the 

 fisheries point of view tlieir influence is not Avholly evil, as some of 

 them are closely associated with pearl production in the oyster. One 

 enemy (a Plectognathid fish) which doubtless devours numy of the 

 oysters, at the same tiuie receives and passes on the })arasite which 

 leads to the production of pearls in others. The loss of some individ- 

 uals is in that case a toll that we very willingly pay, and no one w^ould 

 advocate the extermination of that particular enemy. 



In fact, the oyster can probably cope well enough with its animate 

 environment if not too recklessly decimated at the fisheries, and if 

 man will only compensate to some extent for the damage he does by 

 giving some attention to the breeding stock and '' spat,'" and by trans- 

 planting when required the growing young from unsuitable ground 

 to know^n and reliable " paars." 



Those were the main considerations that imj^ressed me during our 

 work on the banks, and, therefore, the leading points in the conclu- 



