CULTIVATION OF MARINE ANIMALS IN JAPAN 723 



"red current" or "red tide." This is an immense accumulation of 

 a Dinoflagellata, Gonyaulax, causing discoloration of the sea-water, 

 and, in some way not well accounted for, causing in its wake an 

 immense destruction of marine organisms, large and small. 



The "culture pearls" are, I regret to say, either half pearls or only 

 a little more than half pearls, but as regards luster, shape, and 

 size ,they are beautiful beyond expectations, and meet the require- 

 ments completely in cases where only half pearls are needed. 



Pearl-oyster culture is still in its infancy, but its promises are 

 bright. If, in addition to half pearls, full or "free" pearls can be 

 produced at will, as there are some hopes, it will be a great triumph 

 for applied zoology. 



The Ark-Shell, "Haigai" (Area granosa Lischke) 



One of the most interesting cultural enterprises in Japan is that with 

 the ark-shell (Area granosa), or "haigai," as we call it. This was 

 originally, and is at the present day, most extensively carried on at 

 Kojima Bay, near Okayama. This bay opens into the Inland Sea by 

 a narrow mouth, hardly a mile across, and is about eight miles in 

 length by six miles of breadth. The differences between high and low 

 tide-marks are comparatively great here, as in all parts of the Inland 

 Sea, being five to seven feet, and at low tide the whole of the bottom 

 of the bay is exposed, leaving only four river channels which run 

 through the bay to its mouth. This flat is the area utilized for the 

 cultivation of Area granosa. It seems that this idea was present in 

 the minds of some of the people as far back as the sixties in the last 

 century, and was actually put in practice by 1869. At the beginning 

 different individuals undertook the cultivation by themselves, and 

 the conflict of interests soon became the source of endless disputes. 

 People soon getting tired of this, it was agreed in 1886 to form an 

 association in which all the conflicting interests were amalgamated, 

 and, as this worked very smoothly, it was organized in 1890 into a 

 stock company. At present a little over 830 acres of the bottom is 

 utilized, the cultivated areas being scattered mostly along the south- 

 ern and western sides of the bay. The annual sale amounts to 75,000 

 to 100,000 bushels, valued at more than 30,000 yen, and yielding a 

 return of 40 to 60 per cent on the capital invested. 



The method of culture is as follows: By September or October 

 of every year, the Iarva3 of the mollusk, quitting their swimming 

 stage, have become tiny shells not more than two or three millimeters 

 long, buried directly below the surface of the bottom mud. These 

 are collected from various parts of the bay by an ingenious instru- 

 ment, which may be described as a huge comb more than six feet 

 long, being a series of short pieces of wire with their points slightly 



