SEA-FISHERIES LABORATORY. 169 



fish on the bed in relation to sewage outflows and dispersal 

 and defects in the drainage arrangements. As a result of 

 the examination it was found that Bacillus coli could be 

 isolated from the majority of the mussels examined. The 

 presence of this microbe usually indicates the contamina- 

 tion by faecal matters of the shell-fish in which it is 

 found. But unhappily, this organism must now be 

 regarded as present almost everywhere in shell-fish 

 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 detailed results stated in the Report 

 that B. coli was very abundant in several of the mussels 

 examined : these were the ones collected from the piles 

 in the neighbourhood of a break in the pipe. Two 

 mussels in the sample were quite sterile, and in one 

 or two others the microbe was present in very small 

 quantity ; these latter shell-fish 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. 



In this case Mr. Johnstone points out that 

 " it is probable that the faulty condition of the sewer 

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

 these 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 tani at the pumping station 

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



