CULTIVATION OF MARINE AND FRESH-WATER ANIMALS IN .lAI'AN. 283 



iiiid with the ventral margin above. As the mud is 6rm, they seem not only to keep 

 this position, but also to grow finely. They are often cleaned, and as they grow 

 they arc often thinned oul and given more space. In August and September they 

 grow most rapidly. By October they are 6 by 5 inches in size and ready for the 

 market. 1 think the rapid growth, the round shape, and the large size must distin- 

 guish this from the ordinary Japanese species of oyster. This system seems very 

 profitable, as 1 tsubo (6 feel square) is said to give a return of 3 yen. In Formosa 

 there is also a system of oyster culture practiced by the Chinese. Figure 2, plate 

 x, gives a view of an oyster farm near Tamsui, on that island. Large blocks of 

 stone are arranged 1 foot apart in regular rows, and on these the spat is collected 

 and the oysters are left to grow. 



There are various other methods and variations of methods carried on with more 

 or less success in different parts of Japan, and they are increasing every year. 



THE PEARL OYSTER. 



Ariculii martensii Dunker. 



Various kinds of pearl oysters are found in the southern semitropical islands of 

 •Japan, but the only one which is at all common in Japan proper is the species named 

 above. This pearl oyster is found more or less along the whole of the coast of Japan, 

 but there are some localities famous for producing it in quantities. Such are Shinia, 

 Omura (province Hizen in Kiushiu), Noto, Tosa, etc., and some tine pearls have been 

 obtained from these places. As in so many other matters in Japan, there was a time 

 after the restoration of 1868 when the fishery for these precious shells was thrown 

 into a chaotic state, and, as is usual in such a case, carried to an excess, so that the 

 yield of pearls dwindled to almost nothing. 



[p L890 I suggested to a Mr. Mikimoto, a native of Shima, who had grown up 

 and lived in the midst of the pearl-producing district, the desirability of cultivating 

 the pearl oyster. He took up the subject eagerly and began making experiments on 

 it. Soon after 1 pointed out to him also the possibility of making the pearl oyster 

 produce pearls by giving artificial stimuli. Heat once proceeded to experiment on 

 it. The results have been beyond expectations, and to-day the, Mikimoto pearl-oyster 

 farm, put on a commercial basis, has millions of pearl oysters living on its culture, 

 grounds, and is able to place annually a large crop of pearls on the market. 



The Mikimoto pearl oyster farm is in the Bay of Ago, on the Pacific side of 

 central Japan, a few miles south of the famous Temple of Ise. 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 3 to 7 fathoms, and affording most favorable shelter. Somewhat 

 out of the center 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 1,000 acres, has 

 been leased by Mr. Mikimoto. 



