THE DISTRIBUTION OF BACTERIUM COLI 
COMMUNE 
By HARRIETTE CHICK, B.Sc, 1851 Exhibition Scholar 
From the School of Pathology, Thompson Yates Laboratories, Liverpool 
THIS work was undertaken at the suggestion of Professor Bovce, in order to 
study Bacterium coli commune, with special reference to its distribution. 
The significance and origin of the bacillus, when present, especially in sources 
of water supply, were points also which required clearing up, viz. : — How far its 
presence might be considered as an index of pollution by sewage, in which fluid the 
bacillus is known to exist in large numbers. The experiments described later in this 
paper were undertaken with these two objects : — (1) To examine carefully, material 
well-known to be polluted, and, at the same time, material that might be considered 
unpolluted, in order to see if the respective presence or absence of the B. coli could 
be established. It was especially important to definitely ascertain whether, for 
instance, the brooks and rivers of the water supply of a large city like Liverpool 
normally contained the B. coli commune, and, if so, in what numbers. (2) To see 
if there was evidence of multiplication of this bacillus in water, soil, dust, etc., if 
any of these became contaminated ; or whether, on the other hand, the presence of the 
bacillus might be taken as indicative of recent pollution. 
A method had to be adopted by means of which the presence of B. coli commune 
could be demonstrated and a quantitative estimation made. A solid medium was found 
to be much more convenient than a liquid one ; and a carbolized nutrient agar, of 
which a full description is given later, incubated at a high temperature, has been found 
most useful for isolating and enumerating the bacillus. 
It has frequently been stated that, since B. coli commune is widely distributed 
in nature and is often to be found in air, soil, and water from all sources, its presence 
cannot be taken as direct evidence of pollution. Lehmann* describes an experiment 
in which he found, in yeast, a bacillus closely resembling the typical B. coli commune, 
and brings this forward as a reason why the presence of such a bacillus is not a sure 
sign of contamination. Other authors, Kruse,! Stoddart,J Lunt,§ think that these 
examples of B. coli commune, found in unpolluted material, are probably only 
'coli-like' bacilli, and that the presence of the typical, intestinal, B. coli is rarer than has 
been supposed, although various organisms, resembling it more or less closely, are 
* Centralbl.f. Bait, xv, p. 350. J Journ. of Path. 1897, p. 422. 
f Zeitschriftfur Hygiene, xvii, p. 1. § Proc. Jenn. Inst., 2nd series, 1899, p. 249. 
A 
