View report page

5
A species resembling B. aquatilis sulcatus was found once.
One colony was found which at first sight resembled the diphtheria bacillus, but which on subculture
proved not to be this species.
3.—Barking sewage.
In this experiment we examined 167 colonies. In this, the oldest sewage we were able to
examine, we found a marked difference as to the number and character of the species of bacteria present
compared with those of the more recent sewages.
Two moulds were found: one penicillium glaucum, one hitherto undescribed.
Four colonies of a pink torula were found which had the unusual property (in a torula) of very
slowly liquefying gelatine. Also a white torula.
Streptococcus colonies were found five times.
A yellow staphylococcus, which we could not identify, was common, 27 colonies being found.
Diplococcus roseus occurred three times.
Sarcina flava was doubtfully present in one colony.
Bacillus aureus occurred only once.
B. coli communis was not found, and this fact constitutes one of the most striking features in
this sample of sewage. Numerous colonies grew which resembled this species, but these when tested
chemically, produced coagulation of milk in only 12 cases, and these 12 colonies failed to give the other
chemical reactions ofB. coli communis.
B. albus putidus, an organism which we had not previously met with, was, however, abundant
in this sewage, 14 colonies being found. A similar prevalence of this species was found later in the
Crossness sewage.
4.--Crossness sewage.
No careful study was made of the bacteria present in this sewage, owing to the fact that we
were at this period chiefly devoting our attention to a search for the typhoid bacillus, and to its
growth in sewage under varying conditions.
We may note, however, that out of 673 colonies which grew in the plates made from this sewage,
only three were moulds; and indeed in the whole course of our observations on the bacteriology of
sewage, only seven colonies of moulds occurred or an average of only 0.4 per cent. of the colonies
examined.
The prevalence of Bacillus albus putidus was noteworthy, also the number of Proteus cloacinus
described later.
5.—Homerton sewage.
Here our attention was almost exclusively devoted to a search for the typhoid fever bacillus, of
which we succeeded in finding two colonies. We could pay little heed to other organisms present,
though it may be noted that B. coli communis was present, and that we found enormous numbers of
Bacillus fluorescein stercoralis, a species described below. B. mycoides was also found.
Of the organisms present in the sewage from Bridge-street, Homerton, we have no special
notes, having been engaged solely in the endeavour to find the typhoid bacillus. Bacilli closely allied
to B. coli communis were however present in considerable numbers.
description of certain new species of bacteria in sewage.
So little has been done in this field that, had we had the time to devote to the subject, it would
have been easy to describe many dozen species of bacteria which we have met with in the course of our
observations, which have, so far as we can ascertain, not been hitherto described. The complete flora of so
complex a fluid is however the work of a lifetime, and we must be content to describe a few forms
only, which on account of their numerical prevalence, seem to us worthy of special notice, or which, in
one case, are of special beauty.
The species we propose to name and describe are as follows:—
Micrococcus aurora.
Source.—Found in fresh sewage from St. Bartholomew's Hospital.
Form and arrangement.—Slightly oval cocci, 0.7 to 0.8 n in diameter, often as diplococci
separated by a cleft, rarely in short chains of 3 or 4 elements. In broth cultures the cocci are often
arranged in irregular packets. Large irregular torula-like forms occurred once in an agar-agar
culture.
Motility.—Non-motile.
Groivth on gelatine plates.—Colonies first appear on the third day, minute and circular, not yet
pink in colour. Under the microscope they appear granular and slightly irregular in outline. On the
fifth day the surface colonies are less than 0'5 m.m. in diameter, circular, prominent, and pinkish.
After a week the largest colonies are 0.7 m.m. in diameter, those in the depth 0.25 m.m., and of a pale
pink tint. Later the colonies attain a diameter of 1 to 1.5 m.m. and liquefaction slowly occurs after
two to three weeks.
Streak cultures on gelatine show after two days a narrow prominent line of growth of a pale
pink tint, which eventually attains a width of T5 to 2 m.m. and a bright pink colour. Liquefaction
occurs after 14 to 16 days.
Stab cultures in gelatine show definite growth in three days, almost entirely confined to the
surface; in the depth of the gelatine little or no development occurs. A flat layer 4 m.m. in diameter
and of a light pink colour is present on the surface at the end of a week. Liquefaction is extremely
tardy, but some depression of the surface occurs after a fortnight, and distinct commencing liquefaction
in 16 days.