11 



in the course of which baciUus coU remains, while the less 

 resistant non-lactose fermentei's are eliminated. Probably 

 at the late ebb and early flood the water is highly infected with 

 bacillus coli, so that these mussels may alwa^^s contain a large 

 number of this organism. The presence of streptococci 

 suggests a recent fsecal pollution. The nearest point of 

 infection would be the point referred to at the ten- and- a- half 

 mile mark (three miles away) where the Lytham and Ansdell 

 sewers ultimately discharge into the Channel. The presence 

 of streptococci seems to indicate, therefore, that the Training 

 Wall beds are little better than those at Church Scar. The 

 significance of the presence of Friedlander's Bacillus and 

 Bacillus pyogenes fcetidus in the Church Scar and Training 

 Wall samples respectively is not discussed. Conclusions as to 

 the degree of pollution are best based on the occurrence of 

 bacillus coh and streptococci. 



Before concluding this report, thanks are expressed to the 

 Ribble Navigation Committee and to Mr. Cochrane, the 

 Assistant Engineer, for the invaluable assistance given. 

 Without his help it would have been a most unsatisfactory 

 undertaking, if not impossible. The Engineers launch, the 

 " Aid," was placed at our disposal on the two occasions these 

 beds ^\•ere visited, thus enabling a wide area to be examined 

 A\ hile luicovered by the tide in a minimum of time. 



It is, perhaps, not out of place to report on the value of 

 mussels to an undertaking like the Ribble Training Walls. 

 The intention is to make Preston a seaport town, and to 

 accomphsh this it has been necessary to dredge a deep channel 

 as far as the deep water, some 14 to 16 miles away. To 

 ensure the pei-manence of this channel, each bank has been 

 reinforced with rubble practically all the way from the Docks. 

 The constant danger is the washing away of the Avails, as they 

 are only loose stones and easily dislodged by strong tide. 



