2 CEYLON PEAEL OYSTER REPOKT. 



apparently supply the stimulus which leads in the end to the formation of the gem. 

 Many different kinds of shell-fish produce pearls, and these latter differ in quality in 

 accordance with the animal that has deposited them rather than with the nucleus 

 around which they have heen formed. Still, even in the same shell-fish, pearls may 

 differ much, and such differences are due to the nature of the nucleus, to the position 

 in the body, and to the method of formation. 



It is clear that pearls can be formed in several different ways, and recent discoveries 

 show that some of the earlier suggestions are not altogether fanciful but contain an 

 element of truth. The writings on pearl-production are numerous, and it is un- 

 necessary to discuss all the views that have been held. But this report would have 

 little claim to be regarded as even moderately complete if no mention were made of, 

 at any rate, a few of the chief stages in the discovery of how pearls are formed. 



HISTORICAL. 



Our subject being the oriental pearl, it is only appropriate that we should mention 

 first the early Hindu tradition, held even to the present day in the East, that at 

 night or during heavy rain the pearl oyster ascends to the surface of the sea, opens 

 its shell to the air and takes in drops of fresh water which become consolidated as 

 pearls. Pliny and other classical writers record the similar belief that pearls are 

 caused by drops of dew which enter the gaping shell at dawn and reflect the first 

 rays of the sun, while still uncovered by the sea. Another poetical variant is that 

 the pearls are due to the tears of the Nereids. These and other equally fanciful 

 ideas are found scattered through the literature for centuries; and Columbus, we 

 are told, was convinced he had found the locality for orient pearls when he reached 

 a spot, on the coast of Paria, in South America, where the trees grew down into the 

 sea and had their roots covered with oysters gaping ready to receive the dewdrops 

 from the leaves above. 



As an example of an entirely different, but equally imaginative, idea, we have 

 ^Elian's statement that the pearls were formed by a lightning flash entering the 

 opening shell. It must not, however, be supposed that all the views of the ancients 

 on pearl-formation were wholly erroneous, for, as Giard has recently pointed out, 

 Athen.eus states that a certain Androsthenes, who had travelled in the East, 

 compared the developing pearls in the oyster to the Cestode larvae in pork a 

 wonderfully close approximation to the truth. 



Coming to more modern writers, we find many speculations as to more or less 

 mysterious pathological effusions which may become solidified, as to displaced eggs 

 which may form centres of deposition, as to possible similarity to calculi and to galls, 

 and as to calcification of deposits formed around sand-grains, microscopic algae, ova, 

 embryos, and various kinds of minute parasites and other organic nuclei. We shall 

 give here, in tabular form, some of the leading nanus (by no means a complete list) in 



