62 



designated as a coli-like microbe. I have repeatedly drawn 

 attention to this, that whereas the B. coli communis is the 

 typical microbe of faecal matter, the derivation and distribu- 

 tion of many coli-like microbes is at present not sufficiently 

 known and cannot therefore be used for diagnostic purposes. 

 It is therefore satisfactory to find that the American ob- 

 servers* draw the same sharp distinction ; they find that 

 oysters coming from clean, not sewage-polluted, layings have 

 no B. coli communis, although they may on first tests show 

 microbes which are coli-like,f and that in proportion to the 

 pollution of the layings by sewage they contain the B. coli 

 communis. 



Messrs. Clark and Gage give the following table, based on 

 analyses of shellfish and water during three years : 



SHELLFISH AND SHELL WATER CONTAINING THE TRUE 



B. COLI COMMUNIS. 



Statements such as have been repeatedly made (see the 

 Keport of the Bacteriologist of the Sewage Commission ; 

 Dr. Foulerton's paper read at the Folkestone Meeting 1904 

 of the Koyal Institute of Public Health, in the Bacteriology 



* Thirty-fourth Annual Keport of the State Board of Health of Massa- 

 chusetts for 1902, p. 18. 



f Of 58 species which gave the " presumptive " tests, only 12 were 

 found to be B. coli communis (I.e. p. 20). 



