REPORT ON THE PEARL OYSTER FISHERIES 

 OF THE GRJLF OF MANAAR. -PART V. 



PEARL PRODUCTION. 



BY 



W. A. HEEDMAN, F.E.S., 



PROFESSOR OF ZOOLOGY IN THE UNIVERSITY OF LIVERPOOL, 



JAMES HOENELL, F.L.S., 



MARINE BIOLOGIST TO THE GOVERNMENT OF CEYLON AND INSPECTOR OF PEARL BANKS. 



[WITH THEEE PLATES AND SOME TEXT-FIGUKES.] 



THE investigation of a pearl fishery clearly falls into two parts (1) the prosperity of 

 the pearl-producing mollusc as part of the population of the pearl banks, and (2) the 

 production of the pearls. It is the latter subject to which we now come. The 

 preceding sections of this Report have dealt mainly with the pearl oyster as a healthy 

 animal with its distribution, structure and mode of life ; while the Supplementary 

 Reports have made known the many organisms which are associated with the pearl 

 oyster on the banks, and which are inter-related with it in various ways and 

 undoubtedly influence its life and prosperity. 



The present section, on the other hand, treats of an abnormal process. Pearl- 

 formation has often in the past been characterised, with substantial truth, as "a 

 disease " ; and whether the pearly material be deposited around a parasitic worm, or 

 upon a particle of inorganic sand, or over an organically formed calculus, the resulting 

 pearl is in each case a pathological product of the oyster's own tissues. It is always 

 the shell-fish itself that makes the pearl. The pearl-inducing parasite does not 

 produce the pearl any more than the grain of sand does, but either of them can 



B 



