340 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



almost everywhere in shellfish bedded on our coasts, and 

 its significance lies not so much in its mere presence as in 

 its relative abundance. It will be seen from the results 

 stated above that B. coli was very abundant in several of 

 the mussels examined : these were they that were 

 collected from the piles in the neighbourhood of the break 

 in the pipe. Two mussels were quite sterile, and in one 

 or two others the microbe was present in very small 

 quantity; these latter shellfish were collected from the 

 piles some considerable distance from the break in the 

 pipe. Only in one or two of the mussels examined was the 

 degree of pollution at all excessive. 



It is probable that the faulty condition of the sewer 

 pipe is the cause of the greater part of the pollution of the 

 mussels. The eddies caused by the tide round the piles 

 have excavated a shallow gutter directly beneath the 

 sewer pipe. As the tide lays bare the sands, this gutter 

 becomes filled with a mixture of sea-water and sewage 

 flowing from the break in the pipe. Then when the tide 

 begins to flow, some of this water becomes washed up 

 against the mussels on the piles, and the former become 

 polluted. If the sewer pipe were in proper repair, so that 

 all the discharge flowed from its extremity, and still more 

 if there were an intercepting tank at the pumping station 

 and the sewage were only liberated on the ebb tide, I 

 think that the pollution of the mussels would be very 

 slight, and would be due only to the slight amount of 

 general pollution of the sea caused by the sewage from 

 the towns at the entrance to the Menai Straits. 



