154 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
thing at the present time. It is improbable that we have the 
necessary knowledge to enable us to make the recognition, 
but it 1s quite certain that well-planned “ team-work,” carried 
on by some public authority for a year or two, would afford 
the knowledge. 
As it is, our existing methods of assessing the significance 
of bacterial pollution of shell-fish only give us rather crude 
indications of possible or probable risk to the public health. 
In some cases the pollution may be gross and patent, and in 
others it may be so slight as to be negligible, but the majority 
of cases that arise lie between these extremes. Crude indica- 
tions, such as existing methods of analysis give, are good 
enough evidence to justify public authorities in constructing 
and using purification plant, or in making better disposal of 
their sewage. . 
But it may reasonably be urged that they are not good 
enough to be the bases of penal restrictions. They ought to 
be interpreted in the way a statute is construed when the 
issue is a criminal one, that is, literally. An Order closmg a 
mussel bed creates a new offence, which is only immediately 
the infraction of the Order, but which is really the selling, as 
human food, of commodities which involve risk to the public 
health. It ought to be demanded of those making such a 
new offence what is the degree of risk which the Order attempts 
to obviate or minimise, and if this cannot be stated with some 
precision there is really no excuse for making a restriction or 
prohibition that involves fine or imprisonment. 
Experience of such Orders as have been made, or 
attempted, during the last few years shows that the evidence 
on which the creation of the new offence is based is (sometimes 
at least) vague and ambiguous. It may not even be necessary 
for the authority making an Order to disclose its evidence, 
and it is left for those whom the authority proposes to restrict 
under pain of fine or imprisonment to “show cause” why 
