Characters and distribution of the coliform group of bacteria: a detailed and critical study of the literature, having particular reference to the significance of these bacteria in the examination of water supplies, and including the results of some short experiments bearing upon the subject

An eminent psychologist has achieved considerable notoriety in recent years by replying to many different questions put to him: "It all depends on what you mean by 'so- and -so' and what you mean by 'such- and -such'." However justified may have been these Irish answers in the spheres in which they were given, I submit that this same gentleman, had he been a bacteriologist, could with at least equal justification have answered many questions regarding the coliform group of bacteria by saying: "it all depends on what you mean by 'B. coli'. The confusion arising from the necessarily inadequate definition of 'B. coli' by the earlier investigators has persisted in some degree to the present day, so that even now it is necessary to distinguish between:(1) B. coli - loosely applied to mean the entire coliform group and /or any of its members.(2) B. call - even more loosely extended (e.g., "presumptive B. colt ") to include any micro -organism - sporing or otherwise - or mixture of organisms, which can produce acid and gas when grown in a liquid lactose medium.(3) B. coli - properly (in my opinion) applied to mean the definite sub - group termed "Bact. coli, type I, faecal" by the Ministry of Health (1939)(4) B. coli - still more restricted to apply only to the type species, i.e., B. coli communis (Escherich).If, therefore, in the ensuing pages the emphasis on exact definitions becomes tedious, may it be remembered that final decisions have not yet been reached regarding the importance of certain differences between the various types, and that what may to -day seem relatively trivial (as, for example, the Voges-Proskauer reaction in MacConkey's time) may later prove (as the Voges-Froskauer reaction has done) to be fundamental.As quite a number of the tables presented in the following pages have made unavoidable encroachments on both margins, it is respectfully suggested that the outside cover be removed before the work is read