VIII] THE ORIGIN OF PEARLS 97 



In 1857, the German zoologist Moebiiis took up 

 work on pearls and penetrated much more deeply 

 than his predecessors into the mysteries of pearl 

 formation. 



He did not content himself with the fresh-water 

 pearls from his own country but examined those 

 from Indian and American molluscs. Once more, the 

 general absence of the grain of sand as nucleus was 

 noted, and yet again the presence of a worm parasite 

 was put on record. We find about the same period 

 that Dr Kelaart, a medical officer in Ceylon, who 

 was one of the first workers on the Ceylon pearl 

 oyster, repeated the statement that minute parasitic 

 worms were the cause of pearls. . This time — that 

 they were the cause of the true oriental pearls. 

 Numerous investigators followed, but there is un- 

 fortunately no room here for a history of their 

 searchings and theories, and we must skip over the 

 intervening years until we come to the much more 

 definite and recent work of Dubois, Diguet, Jameson, 

 Boutan and Herdman. So far, it will be seen that 

 workers had set themselves to discover the contents 

 of the nuclei of pearls, and it may be admitted that it 

 is by no means an easy task to make out in sections 

 what the organic debris of such nuclei might once 

 have been. 



Now, though we are at present dealing with the 

 history of the parasite theory, it will be of interest to 



D. 7 



