PEARL PRODUCTION 



31 



As these two classes of pearl differ not only in value but in mode of occurrence, it 

 is worth while to contrast their distribution more definitely. If we unite the sub- 

 divisions of the pearl-classes, we find the proportions to be : 



From this it is seen that of the 1,400 oysters, aged from 3 to 3f years, which were 

 individually dissected with the greatest care, only 181 proved to be pearl-bearers, 

 equal to a percentage of 13. 



A remarkable feature of these and other observations we have on record is the 

 relatively great abundance of individuals upon the South-east Cheval containing 

 muscle pearls. On the other hand, as the value of the oysters is chiefly dependent 

 upon the proportion of cyst pearls present, these oysters appeared to be commercially 

 inferior to those of the Mid-east < 'heval a conclusion subsequently proved correct 

 by the actual returns obtained from these two banks during the course of the Fishery 

 of 1903. The proportion of muscle pearls for the South-east Cheval at that fishery 

 was over 90 per cent. Of 94 pearls dissected out, only 9 were cyst pearls. 



Whatever may be the cause of certain pearl oysters containing exceptionally large 

 numbers of muscle pearls, it is worthy of note that the vigorous and healthy oysters 

 of the Eastern Cheval and Periya Paar Karai produced practically all the examples 

 of this class of pearls, there being 1 1 1 muscle pearl-bearers from these banks 

 out of 1,262 oysters, whereas the 138 oysters from the beds characterised by stunted 

 growth the Western Cheval, Dutch Modragam, and Muttuvaratu paars gave but 

 a solitary instance of this class. 



The variation in the number of cyst pearls is due, ultimately, to the relative 

 abundance of the pearl oysters on different grounds and of the Tetra/rhynchus 

 larvae that cause pearl-production, and that ratio must be affected amongst other 

 factors by the abundance of the fish-host of the sexually mature Cestode. 



We give now another tabular statement obtained more recently : 



