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41
DIVISION IL-BACTERIOLQGrICAL.
I—SUMMARY OF THE CONTENTS OF PREVIOUS REPORTS.
1.—SUMMARY OF THE CONTENTS OF THE FIRST REPORT.*
In this Report a description of pome of the methods used in the bacteriological examination
of sewage was given, and the results of the bacteriological examination of nine samples of Barking
and six samples of Crossness crude sewage as regards the total number of bacteria, the number of
spores of bacteria and the number of liquefying bacteria, and as regards the species of microorganisms
present were expressed in the form of a table.

Although prior to the publication of this Report there were numerous records of the total
number of micro-organisms in raw sewage, it is believed that there were few, if any, data dealing
with the systematic examination of samples of crude sewage as regards the estimation of the number of
aerobic bacteria present in the form of spores, the number of microbes causing liquefaction of
gelatine, the number of B. coli and spores of the pathogenic B. enteritidis sporogenes.
Such records were considered to be highly important as preparatory to a study of the effluents
from biological coke-beds. Moreover these records have a special interest from the point of view of
the bacterioscopic examination of drinking water. J Thus pure water rarely contains more than
100-200 bacteria per c.c. and very few, if any, spores in a similar quantity. As regards liquefying
bacteria, these are present in considerable numbers even in very pure waters, but they are for the
most part different in sort from those found in sewage.§ B. coli is not present, or only in small
numbers in water free from any objectionable pollution, and the spores of B. enteritidis sporogenes
are absent from as much, it may be, as 100 to 500 c.c. of a pure water.
It is worthy of note that relatively to the total number of microbes, the number of spores of
bacteria is jnuch greater in surface soils! than in sewage or in water. Further, that pure soils do not
contain the spores of B. enteritidis sporogenes even inasmuch as 10 mgrms. of the soil, whereas impure
soils may contain 10,000 per gramme. Lastly, B. coli appears to be absent from pure virgin soils
and present, it may be, in considerable numbers in soils recently polluted.
Although the estimation of the total number of micro-organisms, the number of spores of
bacteria, and the number of liquefying germs was considered not unimportant, chief stress is to
be laid on the enumeration of B. coli and spores of B. enteritidis sporogenes.
B. coli is an organism characteristic of the intestinal discharge of animals, and especially
abundant therein. Moreover, it may be pathogenic, although it can hardly be considered as a
pathogenic microbe under ordinary conditions and in the usual acceptation of the term. Certainly,
however, its presence serves as an index of the possible presence of other and perhaps dangerous
bacteria of recent animal outcome.
# The Report contained a record of the work done from February 23rd to May 9th, 1898. Filtration of
sewage. Report on the bacteriological examination of London crude sewage. First Report. (P. S. King and
Son, 2 and 4, Great Smith-street, Westminster, S.W.)
J It is remarkable that notwithstanding the fact that sewage is the most common and most dangerous
source of the pollution of drinking waters so little is known of the bacterial composition of sewage.
§ For example: in the Second Report a large number of experiments are given showing that in sewage and
in the effluents from bacterial beds a gas-forming rapidly liquefying microbe described as " sewage proteui " is
present in numbers usually exceeding 100,000 per c.c. This micro-organism was sometimes found to be very
virulent.
+ Report of the Medical Officer, Local Government Board, 1897-8.
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