136 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



it was felt that further laboratory experiments would afford 

 little additional information, and that the details of a 

 commercial process would have actually to be studied in the 

 working plant itself. 



b. Experiments in the open sea. 



It was felt desirable to repeat, in new localities, the 

 experiments in the open already made ; and, in fact, a wish 

 had been expressed by the fishermen at various musselling 

 centres that cleansing works should be started. In September 

 of 1914, Dr. Jenkins and I met Mr. R. W. B. Gardner at 

 Sunderland Point, in the estuary of the Lune, and we then 

 proceeded to visit a place which Mr. Gardner regarded as 

 suitable for relaying mussels for cleansing purposes. This 

 place, with its immediate surroundings, is marked on the chart 

 reproduced at the end of this paper, and described in the 

 explanation, so that I need not further refer to it. There 

 were already some mussels there, and a preliminary analysis 

 showed that these were relatively unpolluted. Mr. Gardner, 

 therefore, laid down a quantity of mussels at this spot, and I 

 made a series of analyses. The mussels were taken from the 

 training wall in the Lune Estuary, a place known to be highly 

 polluted with sewage. A sample examined prior to being laid 

 down for cleansing gave the following results : — 



/Plate 1, 261 red colonies, 1 colourless colony. 

 „ 2,200 „ 3 



„ 3,267 „ 4 



„ 4,200 „ 1 



,, o, 237 ,, 2 ,, ,, 



Mean number of sewage bacteria per mussel = 11,650. 



First Sampling. Relaid for 2 tides. 



5 Plates were made. There was no reduction in the 

 numbers of bacteria contained in the sample. 



l/50th 

 mussel 



