8 PEARLS AND PARASITES 



tains the mature form ; the Tapes or Cardium, which 

 contains the first larval stage ; and the mussel, which 

 contains the second larval stage, which forms the 

 pearl. 



Recently Professor Dubois has been investigating 

 the origin of pearls in another species of Mytilus 

 [M. galloprovincialis) which lives on the French Medi- 

 terranean littoral. The nucleus of this pearl is also a 

 trematode, but of a species different from that which 

 infests the edible mussel. The interest of Professor 

 Dubois' work, however, lies in the fact that he claims 

 to have infected true Oriental pearl-oysters by putting 

 them to live with his Mediterranean mussels. He 

 fetched his oysters, termed ' Pintadin,' from the Gulf 

 of Gabes in Southern Tunis, where they are almost 

 pearlless — one must open twelve to fifteen hundred 

 of these to find a single pearl — and brought them up 

 amongst the mussels. After some time had elapsed 

 they became so infected that three oysters opened 

 consecutively yielded a couple of pearls each. These 

 observations, however, require confirmation, and have 

 been adversely criticized by Professor Giard. 



To return to the Ceylon pearls. The celebrated 

 fisheries lie to the north-west of the island, where the 

 shallow plateaux of the Gulf of Manaar afford a fine 

 breeding-place for the pearl-oyster. The pearl-oyster 

 is not really an oyster, but an allied mollusc known 

 as Margaritifera vulgaris. It lives on rocky bottoms 

 known locally as paars. The fisheries are very ancient 

 and have been worked for at least 2,500, perhaps for 

 3,000 years. Pliny mentions them, but he is, com- 

 paratively speaking, a modern. The Cingalese records 

 go much farther back. In 550 b.c. we find King Vijaya 

 sending his Indian father-in-law pearls of great price ; 

 and there are other early records. From the eighth 

 to the eleventh century of our era the trade seems 

 to have been chiefly in the hands of the Arabs and 



