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5
It will be noted that in the remarks contained in column 5 of Table I. (pp. 8-10) attention is
repeatedly drawn to the presence of certain particular micro-organisms in the sewage. These notes
will now be considered at greater length.
* Bacillus Enteritidis Sporogenes.
This micro-organism was discovered and described by Dr. Klein ; it appears to be causally related
to diarrhoea. Cultivations of B. Enteriditis are extremely virulent; thus, if 1 c.c. of the whey from
an anaerobic milk-culture is injected sub-cutaneously into a guinea pig, it usually causes death in less
than twenty-four hours. The spores of this microbe are abundant in London crude sewage, as may be
seen by referring to table 1, column 5. The results obtained may be summarised as follows:—
Barking crude sewage.
Exp. 2.—B. Enteritidis was detected in a milk-culture containing 0.1 c.c. of crude
sewage, but was absent in milk-cultures containing 0*0001, 00005 and 0.001 c.c. of crude
sewage.
Exp. 7.— B. Enteritidis was detected in milk-cultures containing TO and 0.1 c.c. of crude
sewage, but was absent in milk-cultures containing 0.000l and 0.001 c.c. of crude sewage.
Exp. 10.— B. Enteritidis was detected in milk-cultures containing 0.5 and 0.1 c.c. of crude
sewage, but was absent in a milk-culture containing 0.01 c.c. of crude sewage.
Exp. 14.—B. Enteritidis was detected in milk-cultures containing 0.1, 0.01, and
0.001 c.c. of crude sewage, but was absent in a milk-culture containing 0.0001 c.c. of crude
sewage.
+ In experiment 2, therefore, the number of spores present in 1 c.c. of sewage was at least 10,
but less than 1,000; in experiment 7 at least 10, but less than 1,000; in experiment 10 at least
10, but less than 100 ; and in experiment 14 at least 1,000, but less than 10,000.
Crossness crude sewage.
Exp. 1.—B. Enteritidis was detected in a milk-culture containing 0*1 c.c. of crude
sewage;
Exp. 3.—And in a milk-culture containing 0.01 c.c. of crude sewage ;
Exp. 4.—And in a milk-culture containing 0.01 c.c. of crude sewage ;
Exp. 8.+—And in a milk-culture containing 1.0 c.c. of crude sewage, but it was absent
in milk-cultures containing 0.0001, 0.001, 0.01, and 0.1 c.c. of crude sewage;
Exp. 11.—B. Enteritidis was detected in milk-cultures containing 0.5, 0.1, 0.01 c.c. of
crude sewage ;
Exp. 15.—And in milk-cultures containing 0.1, 0.01 and 0.001 c.c. of crude sewage, but
it was absent in a milk-culture containing 0.0001 c.c. of crude sewage;
‡ In experiment 1 the number of spores present in 1 c.c. of sewage was at least 10 ; in
experiment 3, at least 100 ; in experiment 4, at least 100 ; in experiment 8, at least 1, but less than
10; in experiment 11, at least 100; and in experiment 15, at least 1,000, but less than 10,000.
If sewage be regarded as the most frequent and dangerous source of the pollution of natural
waters; and if, as seems to be extremely probable, it is found that the B. Enteritidis is not present
in pure waters; it is obvious from the above results that, apart from the pathogenic character of this
anaerobe, we are here dealing with a bacteriological method of detecting contamination with sewage,
which excels in delicacy any chemical process known. As the life history of this micro-organism
becomes more fully known, the bacteriologist may not improbably be in a position to condemn a
water for drinking purposes, by merely considering the results obtained in his examination for this
particular organism.
Future work will show what the fate of the B. Enteritidis is during the passage of the sewage
through the biological filters at the outfall works. No doubt it will be said, and perhaps justly so,
that even if the effluents do contain B. Enteritidis this is not necessarily a grave evil in the case
of sewage discharged into a tidal river below locks the water of which is not used for drinking
purposes, unless, indeed, presence of this organism leads, when associated with a large amount of
organic matter, to anaerobic and offensive putrefactive processes in the bed of the stream.
§ Bacillus Coli Communis.
This micro-organism is present in London crude sewage in very great numbers, as the following
figures show—
Barking crude sewage.
Exp. 2.—B. Coli was detected in 0.000025 c.c. of crude sewage.
Exp. 7.—Forty colonies typical of B. Coli were counted in a phenol-gelatine plate
cultivation containing 0.0001 c.c. of crude sewage.
* See Nos. 3 and 14 (Plate I.).
Reference may be made to the" Certralblatt fur Bakteriolog. und Parasitenkunde," Band xviii., N. 241,
Band xxii., N. 5, 20, 21; and Med. Officer of Health Report, Loc. Gov. Board, 1895-6.
† In this experiment the milk was not freshly prepared. If the milk is not fresh and recently sterilised a
much larger quantity of sewage has to be added in order to produce the typical Enteritidis change. A later
experiment, however, seems to show that it is not the age of the culture which inhibits the growth but the presence
of dissolved oxgyen.
‡ In experiments carried out for the Local Government Board by Dr. Klein and myself as regards the
number of spores of B. Enteritidis in crude sewage, we obtained results which correspond with the above.
Although not yet published, these experiments precede the above in point of time.
§ See Nos. 1, 4, 5, 6, and 13 (Plate I.).
The exact part played by B. Coli Communis in processes which aim at the biological purification of sewage
is not known; but the B. Coli Communis, although it does not belong to the class of liquefying bacteria, is
certainly capable of decomposing albuminous matter.