CULTIVATION OF MARINE ANIMALS IN JAPAN 721 



covered up with the silt, they are heaped close together in masses, and 

 are, moreover, washed and cleaned two or three times in a month, at 

 low tide. In April these oysters are stuck into the mud almost ver- 

 tically, with the hinge-end below and with the ventral margin above. 

 As the mud is firm, they seem not only to keep this position, but also 

 to grow finely. They are often cleaned, and as they grow they are often 

 thinned out and given more space. In August and September they 

 grow most rapidly. By October they are six by five inches in size and 

 ready for the market. I think the rapid growth, the round shape, and 

 the large size must distinguish this from the ordinary Japanese species 

 of oyster. This system seems very profitable, as one tsubo (six feet 

 square) is said to give a return of three yen. In Formosa there is also 

 a system of oyster-culture practiced by the Chinese. In oyster-farms 

 near Tamsui, on that island, large blocks of stone are arranged one 

 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 (Avicula martensii Dunker) 



Various kinds of pearl oysters are found in 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 Shima, Omura (Pro- 

 vince Hizen in Kiushiu), Noto, Tosa, etc., and some fine 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. 



In 1890 1 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 I pointed out 

 to him also the possibility of making the pearl oyster produce pearls 

 by giving artificial stimuli. He at 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. 



