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A STUDY OF THE B. COLI GEOUP WITH SPECIAL KEFERENCE 
TO THE SEROLOGICAL CHARACTERS OF THESE 
ORGANISMS. 
By T. J. Mackie. 
Introductory Discussion : The Classification of " Coliform " 
Bacilli and the Biological Relationships of the B. coli 
Group to other Gram-Negative Aerobic 
Intestinal Bacilli. 
In 1885 Escliericli recorded the isolation of a Gram -negative intestinal 
bacillus which he designated B. coli communis, and this classical type has 
been long considered the prevalent intestinal bacterium. In general this 
organism has been described as a motile, non-sporing, aerobic, facultatively 
anaerobic, Gram-negative bacillus, which grows at 37° C, ferments glucose, 
lactose and dulcite with acid and gas j^roduction, forms indol from peptone, 
clots milk, reduces nitrates, and grows in gelatin media without producing 
liquefaction. 
With the advance of bacteriological knowledge and as a result of 
extensive investigations on the bacteriology of faeces, water, milk, etc., this 
original type has come to represent only one of a considerable bacterial class 
or gi oup. The organisms of this group, however, are characteristic normal 
inhabitants of the animal intestine, and are therefore conveniently designated 
by the generic term B. coli. 
Their pathological importance has been well established in virtue of their 
potentially pathogenic properties, and in the bacteriological diagnosis of 
intestinal infections their precise recognition and the separation and 
differentiation of specific pathogenic organisms from them have necessitated 
the most careful study of their biological characters. Moreover their 
occurrence in water supplies has led to an extensive study of the whole group 
from the point of view of sewage contamination, and the importance of certain 
types as indicators of such contamination has been emphasised. Thus, the 
detection of these organisms constitutes an essential method in the routine 
examination of water supplies. This group of bacteria is also concerned in 
the process of souring of milk, and certain of the classical types were 
originally isolated from this source, e.g. B. acidi lactici (Hiippe). 
While the whole group of organisms biologically allied to Esclierich's 
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