546 PROCEEDINGS OF SECTION D. 
every three or four hours. At night, when the ship was usually 
at anchor, these shells were taken out of the tubs and placed in 
specially-constructed cages composed of wired netting stretched 
over rhomboidal wooden frames, this shape offering the least 
resistance to the current. The frames, with their contents, were 
then lowered overboard, and secured by a rope till the morning. 
A small number of specimens, some half a dozen only, were 
simply placed in a shady place on deck, sea water being thrown 
over them at intervals. With a third equally small series an 
experiment was put in practice, and identical with the method 
recently reported to have been attended with remarkable success 
in connection with the conservation of the American oyster for 
long periods out of water. This method, known as “ muzzling,” 
consists of fastening the shells so tightly together with wire that 
the contained liquids cannot escape. Thus treated, the oysters 
are said to survive several weeks’ isolation from their native 
element. All the pearl-shells treated in the several manners 
described were brought into Thursday Island on the second day 
after their collection. Of the examples confined in tubs of sea 
water, renewed at intervals throughout the day and lowered 
overboard in frames at night, every specimen was preserved in 
health. Of the number simply placed in the shade on deck, sea 
water being occasionally thrown over them, one half only arrived 
in good condition, while the remaining half, being too exhausted 
to recover, fell a prey to crabs and predatory molluscs. A like 
untimely end befell all those examples on which the “ muzzling” 
process had been practised. A subsequent study of the case last 
recorded showed that the mortality was brought about through 
the liquid draining away entirely from the animals through the 
byssal or pedal cleft, which retains its full development even 
in the adult shells in which a byssus is no longer present. A like 
explanation applies also, though in a less marked degree, to the 
specimens left on deck, and over which water was thrown at 
occasional intervals. The results of the foregoing experiments 
clearly demonstrate that the mother-of-pearl shell, while of a 
much more delicate constitution than the ordinary oyster, and 
very impatient of prolonged removal from its native element, 
might, with due care and under conditions corresponding with 
those to which the bulk of the specimevs were submitted, viz., 
continued immersion in sea water, be easily transported in a 
living state from the outer fishing-grounds to any desired locality. 
The next step taken was to ascertain the practicability of 
cultivating the pearl-shell brought from the outer fishing-grounds, 
having a depth of seven or eight fathoms, in the comparatively 
shallow inshore waters. With this object, some favourable- 
looking pools in the fringing coral reef, off Vivian Point, and 
immediately beneath the Government residence at Thursday 
Island, were selected. These pools, which were only exposed for 
