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JOURNAL, R.A.S. (CEYLON). [VOL. XVI. 



established, which I doubt) of the parasitic origin of pearls, have pro- 

 tested against the scientific barbarity, which has no excuse, of robbing 

 the pearl oyster— our Ceylon oyster — of its legitimate time-honoured 

 beautiful Greek name, associated with a thousand poetic legends and 

 at least one great Biblical illustration, and substituting for it a vile 

 inappropriate Latin term, which means, not only painted and coloured, 

 but false and counterfeit. But, like a true Englishman, it is the com- 

 mercial, practical aspect of the subject which has engaged his attention, 

 rather than its aesthetic side, so I am not surprised to find him strike 

 the keynote of his Paper in the introductory announcement, that 

 since diamonds like South African shares are going up, the Ceylon 

 Government and the Ceylon Public had better look after their interests 

 in local fisheries, as pearls are sure to follow suit. After such a 

 warning, it is hardly necessary to say that in the selection of his 

 scientific facts he has collated them (if I may be excused the term) so 

 as to keep in view all those that are likely to be of general interest, 

 and eschew what would be technical and comparatively uninteresting. 

 I should have wished, however, he had given the natural history of the 

 bivalve he had selected for his subject, a little more of his attention 

 on the Paper he has read to us, as no one could have dealt with it 

 better with his extensive reading and special researches in this section 

 of Natural Science. I have no intention of detaining the meeting at 

 this late hour, and shall therefore confine myself only to one or two 

 points of practical importance, on which I shall be glad to be 

 enlightened by Mr. Collett. The first refers to the question mooted 

 originally by Dr. Kelaart in his report of 1857 — Are oysters monoecious 

 or dioecious? — in other words, are the two sexes found in separate 

 individuals, or are they all female or hermaphrodite capable of breeding 

 by self-fertilization? Now, according to Dr. Kelaart, who is universally 

 acknowledged to be the highest authority on the subject, there is no 

 proper distinction between the two sexes except in the contents of the 

 ovarium or egg-bag, which in 97 or 98 per cent, contain ova at all stages 

 of growth even from birth, and only in one or two per cent, contains 

 the fluid essential for cross fertilization and no ova at all. These 

 oysters then represent the male individuals, though there is nothing in 

 the external coat or internal structure to distinguish them from the 

 others. The practical importance of this fact comes in with the light 

 it throws on a possible frequent cause of the disappearance of oysters 

 from old oyster beds. For, if cross fertilization be essential to the 

 production of a healthy progeny, as Darwin has established, and large 

 colonies of such progeny growing together are necessary to form a 

 productive "band," as Kelaart has shown, the destruction of the few 

 males by any accidental cause may suffice for the extinction of an 

 entire bank of oysters. Mr. Collett himself, to whom I referred this 

 point before the lecture, was good enough to explain to me that he 

 believed that the female oyster has it in her power to change her sex 

 as often as she chooses, a wonderful fact, if it be the case ; only it is 



