THE ORIGIN OF THE PEARL 21 



The scientist Diguet, who studied this question in the 

 pearl oyster of the Gulf of California, said there were 

 three stages in the development of the pearl. In the first 

 stage there is a sack filled with a translucent, serous 

 liquid, the effusion of which is due probably to irritation 

 caused by a parasite. In the second stage the liquid 

 gradually thickens and assumes the appearance of jelly. 

 Then it changes into conchyolin and the mass divides 

 into concentric layers separated by interstices. The third 

 stage is the petrification or calcination of the pearl by the 

 filling of these interstices with a crystallized calcareous 

 deposit. 



The famous German naturalist, Von Baer, in 1830 

 made the statement that the central nucleus of a pearl 

 was a small animalcule or worm. The Italian naturalist 

 De Filippi, in 1852 again brought out the theory of the 

 parasitical origin of pearls. He attributed the frequency 

 of pearls in the Anodonta cygnea of the Lake of Rac- 

 conigi in the royal park to the presence of a parasitic 

 worm, Distonium duplicatum in the mantle of the mol- 

 lusk. 



In 1856 Kuchenmeister stated that the pearls of the 

 rivers in Saxony, had as their nuclei small ticks, or mites. 

 Mobias devoted considerable time to the pearl oyster 

 on the western coast of America. It was his opinion 

 that the formation of pearls in these mollusks was due to 

 a parasitical worm. Two famous scientists, Kelaart and 

 Humbert, announced that the Cercaria, Filaria, and three 

 other helminths which they found in the pearl oyster of 

 Ceylon, acted an important part in the formation of the 



