90 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



person suffering from, or convalescent from, or a carrier of 

 typhoid fever been living in the area drained by the sewer 

 discharging near the mussel bed, then the shellfish might have 

 become infected and persons eating those shellfish might have 

 contracted typhoid fever. 



But the bacteriological evidence is really weaker than has 

 just been indicated, and I may quote Bulstrode with advantage : 

 The Eeport on " Shellfish other than Oysters," of 1909-10, 

 says : "It was found during the enquiry relative to oysters 

 that bacteriological investigations yielded conflicting results, 

 and it cannot be said that bacteriologists are in agreement as 

 to the standard to be adopted, and this seems to be the case 

 whether regard be had to the total number of organisms 

 present, the percentage proportion of certain organisms or the 

 mere presence of certain organisms. It has also to be added 

 that there are at present no tests which will serve to distinguish 

 sewage micro-organisms of human origin from those of animal 

 origin, and even if it were practicable or desirable to distinguish 

 between the two it would be difficult to fix reliable standards 

 when dealing with estuarial waters draining a whole catchment 

 area, much of which might be devoted to grazing purposes. 



"It is necessary, too, to point out that the standards 

 adopted by some bacteriologists would not improbably serve 

 to condemn every shellfish bed round the littoral. Possibly 

 the time may come when a standard of this nature may be 

 regarded as desirable, but, in the meantime, a useful provisional 

 standard is one based upon topographical and epidemiological 

 evidence." 



The above passage was written over a dozen years ago, 

 but the matter remains precisely where it was then. The 

 conditions at present are these : — 



There is no generally recognised routine method of identi- 

 fying and enumerating the " colon bacilli " found in 

 shellfish. 



