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very properly replies a few days later* that this fact is quite 
in accord with general principles, and was previously 
known. M. Boutan in a letter (20th Jan., 1904) informs 
me that he is on the point of departure for the East in 
order to investigate the matter further. 
Notwithstanding this recent activity, especially amongst 
our French neighbours, there is still a good deal of work to 
be done before the whole process of pearl formation can be 
considered as cleared up. We want to know especially :— 
Ist, The exact details of formation of the pearl-producing 
epithelial sac when deeply placed in the tissues, and 2nd, 
the complete life-history of the parasite inside the sac. 
* Comptes rendus, Soc. Biol., Paris, 19th Dec., 1903, p. 1618. 
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