266 Pearls. 



was once found, in the shape of a parti-coloured 

 Pearl, the top or upper half of which was perfectly 



9 



FrG, 10, PARTI-COLOUREO PEARL, BLACK AND WHITE. 



white, while the other half was perfectly black ; the 

 two parts being separated by a sharp line of demar- 

 cation. It is difficult to explain with satisfaction 

 the cause of so unusual a phenomenon. Some who 

 examined it supposed that the oyster, having been 

 at one time diseased, had first formed a black Pearl, 

 and then on regaining its normal condition, was pro- 

 ceeding to cover the morbid concretion with a layer 

 of healthy white nacre, but was taken from the sea 

 when the work had been only half accomplished. 

 Others have suggested that a part of the Pearl had 

 been coloured by the inky secretion of the squid or 

 cuttle-fish. These cuttle-fishes abound in the waters 

 where the Pearl-oysters find their home, and it is 

 highly probable that the murky pigment, if ejected 

 in the neighbourhood of the oyster, might affect the 

 colour of the nacre and of the Pearl. 



The dark-coloured secretion, or "ink," of the 

 squid and other cephalopods, was formerly used for 

 writing, and is employed in the preparation of sepia 

 and true Indian ink. It is a body of intense 



