Not only is the diver exposed to the danger of attack from sharks, but his hazardous calling is necessarily exhausting, and, as a rule, he is a short-lived man.
There are some kinds of fresh-water mussels which contain Pearls of an inferior quality; perhaps the most celebrated of these is the Pearl Mussel of the Chinese, who make a singular use of it. They string a number of globular pellets, and introduce them between the valves of the mussel, so that in course of time the creature deposits a coating of pearly substance upon them, and forms a very good imitation of real Pearls.
