THE PEARL
	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.
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