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to record the results of further examinations of the deposit upon the coke, and also the examination
of the crude sewage, and of the effluents from the coke-beds.
On May 30th some more coke was obtained from the coke-beds at Barking, and on examination
the same " acid-fast " bacteria were noted.
On May 30th, 20 c.c. of the effluent (dated 16th May) from the thirteen-foot coke-bed at
Crossness were centrifugalised and the deposit stained as above. The result was negative.
On June 1st, 1899, 50 c.c. of Crossness crude sewage and 50 c.c. of the thirteen-foot cokebed
effluent were centrifugalised and stained as before. The result was negative.
On June 7th, 1899, some coke was obtained from the Crossness four-foot coke-bed (one foot
from the surface). Scrapings from the surface of the coke were mixed with a little water and stained
as previously. A positive result was obtained, but the "acid-fast" bacteria were for the most part
shorter and plumper than the tubercle bacillus.
On June 7th, 1899, 1,000 c.c. of Crossness crude sewage, and 1,000 c.c of the thirteen-foot
coke-bed effluent were in each case placed in a sedimentation apparatus. The following day the deposit
(about 4 c.c.) was, in each case, further centrifugalised and thereafter stained, as in the previous
experiments. The result was negative as regards the crude sewage, but in the case of the effluent
a few "acid-fast" bacteria were noted. It may be worthy of note that the other bacteria, which,
by this staining process are, as has been explained, coloured blue, are not chiefly bacillary in form.
Most of them appear as cocci, frequently arranged in zooglœa-like masses, and also as long chains
of cocci (strepto-cocci) extending often right across the field of the microscope. Numerous preparations
subsequently made show that either cocci, or rods so short and rounded at their ends as to
simulate cocci, predominate in microscopic stained specimens made from sewage and effluents, and
not, as might have been imagined, distinct bacillary or rod-shaped forms.
On June 15th, 1899, samples of coke from the four-foot coke-bed (one foot from surface)
and from the thirteen-foot coke-bed (six feet from surface) were examined as previously. A positive
result was obtained, but the "acid-fast" bacteria were somewhat short and plump in appearance.
They were usually collected together in little clumps.
On June 23rd, 1899, some of the deposit from Crossness crude sewage, which collects in the
trough close to the pumping plant, was examined as above. Here a large number of "acid-fast"
bacteria were noted, many of which closely resembled the tubercle bacillus.*
On June 27th, 1899, 20 c.c. of Crossness crude sewage and of the thirteen-foot coke-bed
effluent (dated June 20th, 1899) were centrifugalised in each case, and the deposit stained as
before. In both "acid-fast" bacteria were found, and apparently most in the effluent. The bacteria
were usually arranged in clumps, and the short, plump forms predominated.
On June 30th, 30 c.c. of Crossness crude sewage and of the thirteen-foot coke-bed effluent
(dated June 27) were centrifugalised in each case, and the deposit stained. A negative result was
recorded as regards the crude sewage, but in the preparation of the deposit from the effluent a few
short, plump, red-stained rods were observed.
On July 18th, 1899, 50 c.c. of Crossness crude sewage and of the thirteen-foot coke-bed
effluent were centrifugalised and the deposit stained, as in previous experiments. In the case of the
crude sewage, after prolonged searching, a few short, almost egg-shaped red-stained bacteria were
found. But in the effluent little difficulty was experienced in finding "acid-fast" bacteria.
On July 26th, 50 c.c. of Crossness crude sewage and of the thirteen-foot coke-bed effluent
were centrifugalised and the deposit stained. In the effluent red-stained bacteria were found without
any difficulty, but in the case of the crude sewage the diagnosis was doubtful.
Summarising these results it may be said that the deposit accummulating on the coke in
the bacterial beds contains "acid-fast" bacteria in large numbers. Similarly if a sufficient quantity
of the crude sewage and effluents from the bacterial beds be centrifugalised and the deposit stained
as for tubercle bacilli, the same red-stained bacteria are found in the preparations. Particularly is
this the case as regards the effluent.
As regards the experiments on animals, it is to be noted that the amount of deposit from the
coke, sewage, or effluents introduced into the animal was, of necessity, small, so as to avoid a
rapidly fatal result from the pathogenic bacteria habitually present in the materials used. Had it
been possible to employ larger quantities different results might have been obtained.
Without going into detail it may be said that none of the guinea-pigs died of true tuberculosis.
It is not proposed to speak here of other diseases produced by the injections, or of such
diseases as might be judged to be tubercle on incomplete examination.
There was, however, one notable exception, but here the deposit (which contained many
"acid-fast" bacteria) was not obtained from either the Barking or Crossness cokebeds.
Nevertheless, it was from a coke bacterial-bed, which had been treated with
sewage for a considerable time, and worked on similar lines to those adopted at
the Northern and Southern Outfall Works. Here the guinea-pig died after the lapse of some
weeks, and on examination presented the usual appearance of tubercle infection. Moreover, sections
of the bronchial glands, spleen, and other organs, when appropriately stained, showed the
presence of numerous tubercle bacilli.+ So that in this case at least it is not open to doubt that
some of the " acid-fast " bacteria were those of the bacillus of tuberculosis.
It may be concluded from these experiments that, even if some of the "acid-fast" bacteria
collecting in the coke-beds are those of the tubercle bacillus, they have for the most part lost
their infective power. Nevertheless, the single positive experiment recorded tends to destroy the
belief that none of the bacteria in question are those of tubercle, or that, being tubercle, they have
all lost their infective power.
That some of the "acid-fast" bacteria should be those of the bacillus of tuberculosis is not
* See fig. 6.
† See figs. 8, 9, 10, and 11.