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two objections: (1) That it is inadvisable to apply the term 
‘“ coli communis ’’ to a group of organisms, or even so-called 
varieties, and (2) The tests laid down as essential according 
to the definitions quoted, do not go far enough; the list 
contains too many that are of doubtful significance and 
utility, and too few that are admittedly of greater importance 
in the identification of a bacillus. To discuss this last objec- 
tion first: Houston, Savage and all experienced bacteriolo- 
gists admit, that the tests given above are not of equal 
value in the identification of what they term “‘coli.’’ Thus 
to quote from Savage, ‘‘* Different characters have not an 
equal value. Some, such as the fermentation of sugars, 
liquefaction of gelatine, and acid production in milk are of 
sO permanent a type that for an isolated organism to show 
divergence from a typical bacillus coli in any one of these 
particulars would be to throw grave doubt on its being excre- 
tal at all, while others, such as the gelatine surface colonies, 
and the exhibition of motility, are so subject to variation 
that comparatively little significance can be attached to their, 
perhaps temporary, absence or modification.’’ And again 
in another place he says: ‘‘ Organisms that differ from the 
typical excretal type (bacillus coli communis) only in the fact 
that they show no motility and that their gelatine colonies 
are atypical may be regarded as not having their significance 
diminished on these grounds. Similarly the loss of indol- 
production power would not reduce their significance very 
markedly. On the other hand, the absence of glucose or 
lactose fermentation would at once, in the writer’s opinion, 
exclude the organism isolated from being bacillus coli 
ee all” 
The obvious inference from opinions is, why not do away 
with some of these doubtful tests and substitute for them the 
more important fermentation reactions in sugars such as 
dulcite, adonite and inulin? These are entirely on a parallel 
with the glucose and lactose fermentation referred to as being 
‘“of a permanent character.’’ This is the position taken 
up by MacConkey, in his paper on the Bacteriology of Milk 
(Journal of Hygiene, Vol. IV, No. 3, July 1906), and, follow- 
ing him by Bergey and Deehan, Orr and ourselves. 
