Although
the discoveries so far in Africa are unimportant, it is possible, now
that the unio is known to exist there, that the streams of that
wonderful land of precious things may add a companion gem to the vast
natural hoards there of the diamond. In two years succeeding his first
find, the discoverer secured one hundred and fifty pearls at an average
of one pearl to eight hundred shells!
Authorities
tell us that the nucleus of a mussel-pearl is usually the larva of a
distoma. Nuclei of pearls vary according to the circumstances
surrounding the beds of the shell-fish and those circumstances have
much to do with the occurrence of the pearl.
