722 OCEANOGRAPHY 



The bay, like all in which the pearl oyster grows in abundance, is 

 a very quiet piece of water with a most irregular, highly broken-up 

 coast-line full of deep-running inlets, coves, etc., with a depth of three 

 to seven fathoms, and affording most favorable shelter. Somewhat 

 out of the centre of the bay to the north there is a little island called 

 Tadoko, where the land part of the enterprise, necessary buildings, 

 etc., are placed, and where altogether about 100 persons connected 

 in some way with pearl-oyster culture are now living. Around and in 

 the neighborhood of this island a large area of sea-bottom, which with 

 several large recent additions now amounts to 1000 acres, has been 

 leased by Mr. Mikimoto. 



The farm is divided into two portions: (1) Those parts where the 

 spat is collected and the young are kept to their third year, and (2) 

 the parts where the shells older than three years are kept. The breed- 

 ing-season of the pearl oyster is July to August, and before this comes 

 round namely, in May to June stones six to eight pounds in 

 weight are placed over the bottom of the spat-collecting grounds, 

 which are generally in shallower parts, penetrating deep into land. 

 By August tiny shells not more than three to four millimeters long 

 are first discovered, attached to these stones by their byssus, and the 

 number increases steadily with the season. An immense number of 

 shells is collected every year. They are allowed to lie as they are 

 until November, and then those that are too near the shore are re- 

 moved, with the stones on which they are anchored, into depths greater 

 than five or six feet. This is necessary to protect them from cold, 

 from the effects of which they are apt to die in the course of winter if 

 left in the original places. The young shells are then left quietly and 

 allowed to grow for three years, or, better, some may be removed to 

 deeper waters, and where they are given more space, and get more 

 food, and grow better. At the end of three years, when they are about 

 five to six centimeters, across, they are taken out of the water and the 

 operations necessary for inducing them to produce pearls that is, of 

 putting in nuclei for pearls are performed on them. At present 

 the number thus operated on in a year is only 250,000 to 300,000. 

 They are then put back in the sea and spread out at the rate of 

 about thirty to every tsubo (six feet square), and are left alone for 

 four years more. At the end of that time, or seven years and a half 

 from the beginning, they are taken out of the water and opened. 

 Natural pearls, as well as "culture pearls," as I have named those 

 produced from the introduced nuclei, are thus harvested and put on 

 the market. 



As in all culture enterprises, there are many enemies of the 

 pearl oyster, as well as unexpected difficulties in the way of its 

 culture. Octopus, Codium, Clione (sponges), all sometimes play sad 

 havoc among the mollusks, but the most dreaded enemy of all is the 



