BRITISH PEARLS 5 



opaque than the sea pearl ; so the pearl fisheries of 

 the Welsh and Scotch rivers are falling into disuse. 

 Our ancestors, however, thought otherwise. Less 

 than fifty years ago the Scotch fisheries brought in 

 some i2,ooc a year ; and a writer of the early part of 

 the eighteenth century describes Scotch pearls as 

 'finer, more hard and transparent than any Oriental.' 

 British pearls were highly thought of by the Romans. 

 Pliny and Tacitus mention them ; and Julius Caesar 

 is Tsaid to have dedicated a breastplate ornamented 

 with British pearls to Venus Genitrix. Fresh-water 

 pearls are still ' fished ' with profit in Central Europe ; 

 but the Governments of Bavaria, Saxony, and Bohemia 

 watch over the industry and only grant a licence to 

 fish any stretch of water about once in twelve years 

 a restriction which, had it been imposed on our 

 fisheries, might have saved a vanishing industry. 



In 1871 Garner showed that the pearls in the edible 

 mussel (Mytilus edulis), which is largely used for bait 

 upon our coasts, were formed round the larvae of a 

 fluke, a remote ally of the liver-fluke that causes such 

 loss to our sheep-breeders. This origin of pearls has 

 been more completely followed out by Mr. Lyster 

 Jameson. Nor must we forget to mention the re- 

 searches of Giard (1897) and Dubois (1901) in the 

 same subject. We know the life -history of the 

 organism forming pearls in this edible mussel more 

 completely than we do that of any other pearl-forming 

 parasite ; and, before returning to the Ceylon pearls, 

 we will briefly consider it. 



Mr. Lyster Jameson finds that the pearls of the 

 Mytilus are formed around the cercaria or larval form 

 of a fluke which, in its adult stages, resides in the 

 intestine of the scoter (CEdemia nigra\ and was origin- 

 ally described from the -eider-duck (Somateria mollis- 

 sima) in Greenland and named Leucithodendrium 

 somaterice, after its first known host. The cercaria 



