306 BACTERIOLOGY. 



than that in which it is normally located, and that its 

 occurrence in diseased conditions is not rare, justifies 

 the opinion that it is one of the most important of the 

 micro-organisms with which we have to deal. 



While not generally considered to be a pathogenic 

 organism, there is, nevertheless, sufficient evidence to 

 warrant the statement that, under favorable conditions, 

 with which we are not entirely familiar, this organism 

 may assume pathogenic properties and that its presence 

 in diseased conditions is not always to be considered as 

 accidental, though this is frequently the case. 



The morphological and cultural peculiarities of the 

 bacterium eoli commune are as follows : 



Morphology. In shape it is a rod with rounded 

 ends, sometimes so short as to appear almost spherical, 

 while again it is seen as very much longer threads. 

 Often both forms will be associated in the same culture. 

 It may occur as single cells or as pairs, joined end-to- 

 end. There is nothing to be said of its morphology 

 that can aid in its identification, for in this respect it 

 simulates many other organisms. It is usually said to 

 be motile, and undoubtedly is motile in the majority of 

 cases, but its movements are so sluggish that a positive 

 opinion is often difficult. 



By Loffler's method of staining, flagella can be 

 demonstrated, though not in such numbers as are seen 

 to occur on the typhoid fever bacillus. 



It does not form spores. 



It grows both with and without oxygen. 



On gelatin. When on the surface its colonies appear 

 as small, dry, irregular, fiat, blue-white points that are 

 commonly somewhat dentated at the margin. They 

 are a trifle denser at the centre than at the periphery, 



