PEARL-CULTURE AND PEARL-FARMING 291
pellet was the only foreign substance protruding on the inside of the shell.1
The oysters were returned to the sea without further injury, and after
the lapse of a month the pellets were found covered with thin layers of
nacre.
Experiments
in growing pearls in the abalone or Haliotis were made in 1897 by Louis
Bouton, an account of which was given at the meeting of the Paris
Académie des Sciences in 1898.2 The tenacity of life in this
mollusk makes it especially desirable for experiments of this nature.
Through small holes bored into the shell, pellets of mother-of-pearl
were inserted and placed within the mantle, the small holes being
afterward closed up. Other nacreous pellets were introduced directly
into the bronchial cavity. The objects were soon covered with thin,
pearly layers, resulting in a few months in spheres of much beauty,
resembling somewhat the pearls naturally produced by this mollusk. In
six months, according to M. Bouton, the layers became of sufficient
thickness to be attractive. Within limitations, the size of the pearl
produced is in proportion to the length of time it is allowed to remain
within the mollusk. The results of the experiments seem to encourage
further efforts in this line, and possibly in course of time there may
be a profitable business in growing pearls in abalones on the Pacific
coast of the United States. Indeed, the experiments in transplanting
and cultivating the pearl-oyster in Australia leads one to fancy that
the culture of that species in the warm coastal waters of America is by
no means an impossibility.
Many
other experiments along similar lines have been made more recently. An
interesting feature of attempts made by Mr. Vane Sim-monds of Cedar
Rapids, Iowa, in 1896-1898, is that in order to avoid straining the
adductor muscles by forcibly opening the shell while the mollusk
resisted the intrusion, each selected Unio was exposed in the open air
and sunshine until the valves opened; then a wooden wedge was carefully
inserted in the opening, and the mollusk immediately immersed in water
to revive it or to sustain life. After a few moments of immersion, the
operator carefully raised the mantle from the shell, inserted the
pellet of wax or other small article to be covered with nacre, drew the
mantle to its normal position, removed the wedge, and returned the
mollusk to a selected place in the stream at sufficient depth to avoid
danger of freezing in winter.
Probably
it would be more satisfactory to stupefy the mollusks by means of some
chemical in order to insert the pellets. Marine mollusks have been
successfully stupefied by slowly adding magnesium sulphate crystals to
the sea water until the animals no longer respond
1 "La Pêche et la Culture des Huîtres Per- 2 "Comptes Rendus de l'Académie des
Hères à Tahiti," Paris, 1885. Sciences," Vol. CXXVII, pp. 828-830.
