commonly
the nuclei of Indian pearls. It is interesting also to learn that Mr.
James Hornell (inspector of the pearl banks) finds these worms in
another stage in the file-fish, which frequents the banks to prey upon
the oysters, and confidently expects to find them in the adult stage
in the shark, which in turn devours the file-fish.
It
is the opinion of Jameson of London and others, that the parasite which
causes the formation of pearls in the mussels of Europe is frequently
the larva of distomum somaterce, from the eider-duck and scoter, and
that the larva first inhabits Tapes, or the cockle, before getting into
the mussel.
Generally
the nuclei appear to be the bodies or eggs of minute parasites—distoma,
filaria, bucephalus, etc., and they vary in different localities
according to the animal life of the neighborhood. In the still parts of
the river Elster, where water-mites (Limnochares ano-dontce) were
abundant, Kuchenmeister found that the mollusks contained more pearls.
