NO. 51.— 1900.] PEARL FISHERIES. 



171 



may be explained. The most generally prevalent nuclei 

 appear to be the bodies or eggs of minute internal parasites- 

 such as Filaria, Distoma, Bucephalus, &c. This was pointed 

 out by the late Dr. Kelaart, in his Report to the Ceylon 

 Government on the Pearl Oyster of Aripo ;* and his obser- 

 vations were supported by Humbert, the Swiss Naturalist, 

 who accompanied him to the pearl banks in 1859. More 

 recently, similar observations have been made by Mr. Edgar 

 Thurston, of the Madras Museum,! and the latest conclusions 

 of Science appear to be entirely favourable to the " parasite " 

 theory. 



The fact that pearls may be artificially produced by 

 inserting small shot or grains of sand between the mantle 

 and the shell of the animal has long been known. The 

 Chinese have been specially successful in producing pearls 

 in this way ; but the best of them are of inferior colour and 

 brightness, and their value is comparatively insignificant. 

 Linnaeus, who was aware of the possibility of producing 

 pearls artificially, suggested the collection of a number of 

 mussels, piercing holes in their shells with a fine auger to 

 produce a wound, and afterwards " parking " them for five 

 or six years to give the pearls time to grow. The Swedish 

 Government consented to try the experiment, and long did 

 so. Pearls were produced, but were of little value, and the 

 enterprise was finally abandoned as unsuccessful. 



The distinction between fine pearls and these intrusive 

 bodies coated with nacre was recently demonstrated in an 

 important Paper read before the Academie des Sciences, 

 Paris, by M. Leon Diguet. He alleges that the latter have 

 only the irridescence of mother-of-pearl, and are in origin 

 analogous to the deposits which increase the shell. The true 

 pearl, he contends, has no connection with the shell itself, 

 but is a pathological calcification or " stone," and seems to 

 arise from parasites. It begins with a small sac of humour, 



* " Report on the Natural History of the Pearl Oyster, Trincomalee," 1859. 

 t " Pearl and Chank Fisheries of the Gulf of Mannar," 1894, p. 18. 

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