82 



only half or three-quarter pearls being broadly attached to the nacre 

 of the shell; their size, shape and lustre are however fully equal to 

 those of the natural detached pearl and where the setting does not 

 demand whole pearls they are equally effective ; at the Milan Exhibi- 

 tion, beautiful culture pearls very well set and looking like whole 

 pearls, attracted much attention. The defect is due doubtless to tho 

 method of stimulation which is the introduction of a foreign body, 

 e.g., a nucleus of mother-of-pearl, or a small natui-al pearl (the process 

 is of course secret both as to the precise nature of the irritunt and the 

 method of its introduction) inserted into the oyster ; tliis being 

 weighty sinks on to the lower shell and is there enveloped by the 

 living nacre. As usual in Japan a special zoological scientist has been 

 employed at the farm for years studying the oyster, and there are 

 hopes of the production of free pearls, doubtless by inoculation with 

 the proper parasite. It is one of tho curiosities of nature that the ces- 

 tode parasite which is probably the irritant cause of most natural pearls 

 and which, as in other cases, demands at least two hosts for its life 

 course, is the immediate product of the pearl oyster's most destructive 

 enemies such as the file fish and the skate ; in the latter it finds its 

 full development, and its larvas, ejected from the skate, are absorbed 

 by the oyster and when possible, sepultured in pearl. Hence it may 

 result that too great an exclusion of the oyster's natural enemies may 

 develop the oyster to the detriment of the pearl. This seems a field 

 for Indian study, and it is possible that the future of the Indian poarl 

 may lie in secluded bays rather than in the Straits of Mannar infested 

 with every enemy whether the minute boring , sponge, the file fish and 

 ray, and other destructive fauna, or the mill-race currents which 

 sweep through the straits and smother the beds with sand. It is 

 hoped hereafter to mention localities for such cultivation ; meanwhile 

 local suggestions would be most acceptable. 



174. Area granosa. —The cultivation of this shell is worth mention- 

 ing : the account is from Prof. Mitsukuri's pamphlet. Here, as in 

 the case of the edible oyster, the fiats exposed by the ebb tide which 

 falls some G feet are utilized, and the value of associations is shown 

 by the fact that when cultivation was begun in the sixties of the IQih 

 century it was carried on by separate individuals who soon began to 

 quarrel to the probable wrecking of the new industry ; they accord- 

 iuj^ly amalgamated of their own accord in 1866 into a Fishery associa- 

 tion (before the law of Fishery Association was passed); in 1890 

 this became a Joint Stock Company. The annual return on capital on 

 a cultivation of about 830 acres is said to be between 40 and 60 per 

 cent., and the outturn between 75,000 to 100,000 bushels or above 

 100 bushels per acre. The methods are simple, viz., the raking up 

 from the mud of the tiny shells immediately after tho mollusc has 

 quitted its free swimming stage, and strewing these shells, then only 

 about 1/10 of au inch across and averaging about 85,000 to the quart 



