156 BACTERIAL TREATMENT OF SEWAGE 



unfavourable medium for the growth of the typhoid bacQlus, which 

 in all probability would die out in a few days' time. In crude 

 unsterilised sewage it is clear that owing to competition and the 

 inimical effect some of the non-pathogenic species have upon B. 

 typhosus* that the death of that organism is, in sewage, " probably 

 only a matter of a few days or at most one or two weeks." MacConkey 

 found that in sterilised crude sewage inoculated with the B. typhosus, 

 this bacillus is recoverable in seventeen days, though it does not appear 

 to multiply. In ordinary crude sewage so inoculated, the bacillus 

 was recoverable after thirteen days.-]- 



Of the organisms which we have named as normally present in 

 sewage, it is unnecessary to speak in detail, with the exception of the 

 Bacillus enteritidis sporogenes of Klein.j This bacillus is credited 

 with being a causal agent in diarrhoea, and has been isolated by 

 Dr Klein from the intestinal contents of children suffering from 

 autumnal diarrhoea, and from adults having "English cholera." It 

 has readily been detected in sewage from various localities, and also 

 in some sewage effluents. It has been separated from ordinary 

 milk, even from what was termed by the trade " sterilised " milk. 

 The biological characters of this bacillus are briefly as follows. It 

 is in thickness about equal to the bacillus of quarter-evil, thicker and 

 shorter than the bacillus of malignant oedema, and standing therefore 

 between the latter and the bacillus of anthrax. It is motile and 

 possesses flagella, but does not assume a thread form. It readily 

 forms spores, which develop, as a rule, near the ends of the rods, 

 and are thicker than the bacilli. They can withstand a tempera- 

 ture of 80° C. for fifteen minutes. The bacillus takes the Gram 

 stain. In various media it produces gas rapidly. Particularly 

 is this so in milk. It is an anaerobe, and may be isolated by the 

 following method. A small quantity of the suspected matter is 

 added to a tube of fresh sterilised milk, which is then heated in a 

 water-bath to 80° C. for fifteen minutes. It is then cooled and 

 incubated at blood-heat in a Buohner's tube (see p. 478). In twenty- 

 four hours the milk is coagulated into white stringy masses and small 

 casein coagula, whilst a large portion of the test-tube is filled with 

 gas or a thick, watery, slightly-turbid whey. It is necessary to 

 differentiate the B. enteritidis sporogenes from the bacilli of malignant 

 oedema and symptomatic anthrax and the Bacillus hutyricus of Botkin. 

 For such differentiation it is important to remember that the 

 enteritidis organism (a) stains by Gram's method, (6) in gelatine culture 



* Klein reports that although B. typhosus can live in crude sewage, it is only 

 for a short period. When sewage is diluted with large quantities of water the case 

 is different. 



t Royal Commission on Sewage Disposal, Second Report, 1902, p. 62. 



J Anmial Report of the Medical Officer of the Local Oovemment Board, 1897-98, 

 pp. 210-250. 



