Thus there are two courses open to the cercaria when it has once found its way into the mussel; it either forms the nucleus of a pearl and perishes, or it is swallowed by a scoter, becomes adult, and prepares to carry on the race. But how do the cercariæ make their way into the mussel, and whence do they come? At present their birth, like that of Mr. Yellowplush, is ‘wrapped up in a mistry.’ We may presume that the eggs make their way out of the scoter into the sea-water, and that there they hatch out a free-swimming larva, which, after the manner of trematodes, swims about looking for a suitable host. Within this host it would come to rest and begin budding off numerous secondary larvæ, in which stage it may assume considerable size and becomes known as a sporocyst. No one, however, has seen the eggs hatch, or the free-swimming larva; but Mr. Jameson produces evidence to show that the sporocyst stage occurs in two other common molluscs—viz., in a clam (Tapes decussatus) and in the common cockle (Cardium edule). The former mollusc abounds in the black gravelly clay which forms the bottom of the mussel-beds at Billiers; and every specimen out of nearly two hundred examples investigated by Mr. Jameson was found to be infested with sporocysts containing larvæ closely resembling those which act as pearl-nuclei in the edible mussel. Exactly similar sporocysts were found in about fifty per cent. of the common cockles examined in the Barrow channel, where the species Tapes decussatus does not occur.
Within the sporocyst certain secondary larvæ are formed, as is habitual with the flukes. These secondary larvæ are the cercariæ; and it is in this stage that the animal makes its way into the pearl-mussel and ultimately forms the nucleus of a pearl. Precisely how it leaves the sporocyst and the first host—i.e., the Tapes or Cardium—is not known. Certain experiments made by Jameson, who placed mussels which he thought were free from parasites in a tank with some infected Tapes, are not quite conclusive, and have been ably criticized by Professor Herdman. It is true that, when examined later, the mussels were well infected; but it was not definitely shown that they were not infected at the start; and further, the numbers used were too small to justify a very positive conclusion. Still, on the whole, it may safely be said that life-history of the organism which forms the pearls in Mytilus edulis probably involves three hosts: the scoter, which contains 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 Mediterranean 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, comparatively 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 Persians; and many references to it occur in their literature. Marco Polo (1291) mentions the pearls of the kings of Ceylon; and in 1330 a friar, one Jordanus, describes 8,000 boats as taking part in the fishery. Two centuries later, a Venetian trader named Cæsar Frederick, crossed from India to the west coast of Ceylon to observe the fishery; and his description might almost serve for the present day, so little do habits alter in the East.
The records of the Dutch and English fisheries are naturally more complete than those of their predecessors. The last Dutch fishery was in 1768, and the first English was in 1796, before the fall of Colombo. The fishery is not held every year, but at irregular intervals; and sometimes these intervals have been long. For instance, the oysters failed between 1732 and 1746, and again between 1768 and 1796, under the Dutch régime, and from 1837 to 1854 under the English. On the other hand, the fishing is sometimes annual; recently, it took place with great success in 1887 and the four following years, culminating in the record year 1891, when the Government’s share of the spoil amounted to close upon one million rupees. After this there was a pause till 1903, when the fishery became annual.
The Lieutenant-Governor, Sir Everard im Thurn, now Governor of Fiji, has given a lively account of the fishing scene. He tells us that every year, in November, a Government official visits the oyster-beds, takes up a certain number of oysters, examines them for pearls, and submits his results to certain Government experts. If, as they have done recently, these experts pronounce that there will be a fishing, this information is at once made known; and, partly by advertisement, but probably more by passing the word from man to man, the news rapidly spreads throughout India, up the Persian Gulf, and to Europe. In the meantime preparations on a large scale have to be made.
‘On land, which is at the moment a desert, an elaborate set of temporary Government buildings have to be erected for receiving and dealing with many millions of oysters and their valuable if minute contents. Court-houses, prisons, barracks, revenue offices, markets, residences for the officials, streets of houses and shops for perhaps thirty thousand inhabitants, and a water-supply for drinking and bathing for these same people, have to be arranged for. Lastly, but, in view of the dreadful possibility of the outbreak of plague and cholera, not least, there are elaborate hospitals to be provided.’
By March or April some hundreds of large fishing vessels have assembled at Manaar; and a population which varies during the next two months between 25,000 and 40,000 souls has gathered together.
The fishing-boats leave early in the morning for their respective stations; and, on reaching them, the Arab and Indian divers descend, staying under water from fifty to eighty seconds, and eagerly scooping up the oysters and depositing them in baskets slung round their necks. By midday the divers are worn out; and at noon a gun is fired from the master-attendant’s vessel as a signal for return. The run home may take some hours, according to the distance and the wind; and it is during this time that a considerable number of pearls are said to be abstracted. The men on the boats are occupied with the sorting of the oysters and cleaning them of useless stones, seaweed, and other objects which are gathered with them. The finest pearls lie just within the shell, embedded in the edge of the mantle; and these readily slip out and are concealed about the person of the finder. The Government does what it can to check peculation and keep a guard on each boat; but, in spite of all its efforts, there seems no doubt that many of the ‘finest, roundest, and best-coloured pearls’ pass into the possession of those who have no right to them.
On reaching the shore the oysters are carried to the Government building or ‘Kottus,’ a vast rectangular shed, where they are divided into three heaps; two of these fall to the Government, and the third belongs to the divers. This latter share the divers sell as soon as they quit the ‘Kottus,’ sometimes parting with dozens to one buyer, and sometimes selling as few as two or one. In the meantime the Government’s two-thirds have been counted and are left for the night. At nine o’clock in the evening these oysters are put up to auction. The Government agent states how many oysters there are to dispose of, and then sells them in lots of one thousand. Some rich syndicates will perhaps buy as many as 50,000 at prices which fluctuate unaccountably during the evening. Within a short time the price will inexplicably drop from thirty-five rupees to twenty-two rupees a thousand, and may then rise again as suddenly and inexplicably as it sank. Early in the morning each purchaser removes his shells to his own private shed, where for a week they are allowed to rot in old canoes and other receptacles for water, and are then searched for pearls. For a couple of months this great traffic goes on, until the divers are thoroughly exhausted, and the camp melts away.