PRODUCTS FROM THE SEA
’
3473
formed inside the mantle tissue and so uneOnnecte‘d with.
the shell, may be produced inthis manner.
Parasites
certame cause the formation of péarls, & view which was
'
rst advanced in 1 5 54 and has been proved by the disCovery '
of mummied remains of.dierent parasites in the centre
or
“
nucleus ”
of
many pearls.,
The parasite which
,
most
frequently causes pearl formation. in the Ceylon
pearl oyster is the early stage-of a tapeworm which becomes
_
adult in a large ray which, as we saw in Chapter IX,
'
habituay feeds on these oysters thereby infecting itself
‘
with the
After becoming mature, the
_
worms lay eggs which passintothe seawhere they may nd
_
a temporary home in an oyster. A temporary home if the
oyster is swalloWed by the ray shortly. after, but a
if the oyster shouldbe provoked to protect itself from the
—
irritating parasite by obating ' it with pearly substance…
It may be that pearls are also formed round tiny granules
,
of waste matter produced—by the oysters themselves…
The process of pearl formati0u is perfectly, straight—
forward.
The nucleus, pff—whatever irtating substance
that may' happentobe,beCûîôS
within a tiny
Ï
chamber in the tissues
of Which is produced
the pearly substance whichis composed of
the same nacreous
material which
the
_
“
mother—of—pearl.f’. This is applied inthe regular‘layers
f around the nucleu‘s so that
formed,
te lustre of—which
'
Crystalline nacre (Plàfèâ‘I—2‘3"
_
';;
:The most .—fam011s
_
off, the—. coast of
TheGovernmentcontmlsthe ‘
—
oysterbeds and only allows asherywenapæmus
'
inspeètiçän—. has shoWnithere ‘are suitablefnumbe‘rÿs‘jnffoysters
' _
wh1ch1s by» no
,
'
th1rtynmeshenessmcethebegmnlng0f’helaStœmury ,. ‘
,-.