io8 Pearls. 



crude fancies and curious fables have gradually 

 passed away. It is the object of the present chapter 

 to present a rational explanation of the origin^ and 

 formation of Pearls, so far as the lights of our 

 present knowledge can guide us in solving these 

 difficult problems. 



For a long time it was currently believed that 

 Pearls were found only in diseased shell-fish, and 

 to this day in some parts of Great Britain, when 

 a Pearl is discovered in a mussel or oyster, the 

 edible part is thrown away as unfit for use, while 

 the Pearl, however valueless, is carefully preserved. 

 Hence we often find, even at the present day, that 

 Pearls are alluded to as " morbid secretions." 



On this subject, Professor Coutance, of the 

 Medical School of Brest, has some remarks which 

 are at once sensible and amusing: — "Au point 

 de vue physiologique, I'huitre ne fait, en produisant 

 la Perle rien d'anormal, puisque la nacre de la 

 coquille est formee de la meme substance. EUe ne 

 tire de son fond aucune matlere nouvelle poure faire 

 la Perle : elle y emploie seulement, peut-etre au 

 prejudice de sa coquille, une part de lelement car- 

 bonate qui constitue celle-ci, ou sert meme a la 

 reparer. La maladie de I'huitre n'est done qu' une 

 hypersecretion ; c'est sans doute beaucoup, et nous 

 continuons a la plaindre, comme nous plaignons un 



