THE SHELLFISH INDUSTRY
311
may be are liable to be taken into the stomachs of the
shellsh which feed on any small particles in the water,
and,though they are themselves unaected, they mayin
this manner become a medium for the dissemination of
typhoid and other pathogenic bacteria-. Rigorous regula—
tions forbid the sale of polluted shellsh but the risk of
disease has been an important, and in the past, not un—
justied reason for the undoubted prejudice against the
use of shellsh as a food.
The best preventive measure would undoubtedly be to
forbid the discharge of unpuried sewage in the neighbour—
hood of shellsh beds, but unfortunately this is quite
.
impracticable at the present time.
The only alternative
is to
purify the shellsh and this has been donewith
striking success at Conway, where the extensive mussel
beds had led to the development of a considerable industry,
the collected mussels beingsold to-the large Midland towns.
After an adverse bacterioldgical report the sale of these
mussels was prohibited in 1912 and many men: were throwri
out of employment so that the Corporation of Conway started
'
investigations, later taken over by the Ministry of Fisheries,
_
in the hope of nding some method whereby mussels could
.
_
be puried.
This has to be carried out under articial
_
conditions and for this purpoSe large concrete tanks were
,
constructed and, after lengthy experiments, a simple but
eminently successful method of purication was devised;
The mussels, Which are br0ught to the tanks
sacks by
the
,
shermen are spread two'deep on wooden grids in the
bottom of shallow tanks, as shown in Plate“ III, and
'
.
thoroughly hosed so as to cleanthe outside: otthe shells.
,
Sea water, which has been sterilized by the additi0n
of
..
.
'chloride of lime, any ireeï chloride being -converted
into
common salt by- the
Sodium thiosulphate,
then
.
run in _by gravity from storage tanks, “and the mussels