24 
ANIMAL LIFE ON THE 
could be attributed to the same cause, but it must be 
traced to other sources than an inherent poison in the 
mollusc itself. 
Shellfish in the vicinity of towns should be strictly 
avoided, particularly where common sewers and decaying 
refuse are liable to spread filthy, unhealthy matter along 
the shore. Care should also be taken that they should 
never be gathered from pieces of cast-ashore wreckage 
strewn along the beach, as many kinds of timber contain 
deadly poison ; nor off the tops of metal articles, so 
numerous on town shores, which may be brass or zinc, 
and liable to throw off verdigris and other poisonous 
substances. From these causes alone do shellfish become 
poisonous and dangerous to the eater ; and as I am con- 
vinced that these facts are not so widely known as they 
might be, for the health's sake of the thousands of shellfish- 
seekers who annually spread themselves along the shores of 
our far-stretching firth, I commend them to the special 
notice of my readers. 
As an article of commerce, however, the mussel out- 
strips all its compeers. To it we are almost exclusively 
indebted for the thousands of tons of round fish, fresh and 
cured, that flood the markets and streets of every town and 
hamlet in the land. From John O'Groats to Land's End 
it is the favourite bait for long-line fishing, and for that 
purpose alone it is of inestimable value. 
East Coast fishermen greatly prize it, and jealously 
guard from depredators their mussel-beds, which are 
generally imported from far-distant quarters. 
Some notion of the importance of the mussel in this 
respect may be gathered from the following, published by 
the Fishery Board in answer to several questions addressed 
to them by Her Majesty's Secretary for Scotland, May, 
