394 APPLIED BACTERIOLOGY 



If in a sample of water two or more organisms character- 

 istic of excremental dejecta are found in association with 

 the bacillus coli — say, for instance, the Proteus vulgaris 

 and the sewage variety of Proteus Zenkeri — this should 

 be regarded as almost positive evidence of pollution 

 with sewage. 



It is necessary to point out, when investigating the 

 characters of organisms in connection with sewage pollu- 

 tion, that there exist in sewage and in water, particularly 

 when the latter is polluted with manure or with sewage, 

 in addition to the aerobic organisms, certain others which 

 in the ordinary bacteriological analysis of water, sewage, 

 and other materials are generally overlooked; these are 

 organisms which grow only anaerobically, and which, there- 

 fore, do not make their appearance in the ordinary plate 

 cultures. Although as a rule they are neglected in water 

 and sewage analysis, they are, nevertheless, by their 

 numbers and by their functions not without importance. 

 The anaerobic bacilli are endowed with the power of more 

 or less rapidly peptonising and decomposing gelatine, of 

 rapid multiplication in grape-sugar gelatine or grape-sugar 

 agar in the depth, and of forming gas. Their spores can 

 be heated to 80° C, for half an hour or an hour, without 

 interfering with their subsequent power of germination into 

 the bacilli. 



In this connection, as has already been mentioned else- 

 where, Klein traced an outbreak of severe diarrhoea to a 

 sporogeneous virulent anaerobic bacillus, B. enteritidis 

 sporogenes, which in morphological and cultural respects 

 has some points in common with the bacillus butyricus. 



Furthermore, showing the importance of these organ- 

 isms, it was stated by Klein (Harben Lectures, 1896) 

 that he had recently occasion to examine a sample of 

 sewage effluent which had been subjected to a certain 



