View report page

37
has but one flagellum, whereas Froteus vulgaris is generally stated to bo multi-flagellated; sewage proteus
has smaller and shorter rods than Proteus vulgaris-, sewage proteus shows no "swarming islands" unlike
Proteus vulgaris. This organism has been called sewage proteus owing to its prevalence in crude sewage, and
because of its superficial resemblance to Proteus vulgaris, and to other members of the proteus group. It is not
unlikely that this micro-organism is frequently mistaken for the true Proteus vulgaris It also differs in a
number of important respects from Bacillus proteus urinae, an organism isolated from the urine of a patient
suffering from cystitis by Dr. Horton Smith, and carefully described by him in the Journal of Pathology and
Bacteriology, December, 1896.
It must not, however, be supposed that Proteus vulgaris is not present in London crude sewage, but that
its numbers are not as great as seems to be generally supposed. In figure 1, Plate I., a micro-photograph is shewn
of the true proteus, which was isolated from a sample of Crossness raw sewage. The preparation was obtained by
making a surface gelatine plate culture of this micro-organism, and then making "impressions" from the
"swarming islands" produced by its growth on the surface of the gelatine in 20 hours at 20° C.
A culture of "sewage proteus" proved to be very virulent. Thus, 1 c.c. of a 24 hours' broth culture was
injected subcutaneously into a guinea-pig. The animal was found dead on the second day, but had probably
died on the preceding day. The organism was recovered from the heart's blood in pure culture. [Subsequent
work yielded in some measure anomalous results. Thus, as freshly isolated from sewage, "sewage proteus"
sometimes grew well at 37° C., and sometimes in an imperfect manner. Moreover, the cultures were in some
cases virulent and in others not.]
4.—Bacillus Frondosus.
[An aerobic, non-chromogenic, motile, slowly liquefying bacillus.]
Source.—London crude sewage: gelatine plate cultures heated to 80° C. for 10 minutes.
Morphology.—Large bacilli, with rounded ends ; solitary, in pairs, and in chains of varying length.
Motility.—Motile.
Spore formation*.—Forms spores readily at the room temperature.
Temperature.—No growth at 37° C. Grows fairly rapidly at the room temperature.
Gelatine plate cultures†.—The surface colonies appear as white, coarsely granular films of irregular shape,
which send out curious processes of varied form. These grotesquely-shaped processes resembles bits of seaweed
flattened out. Liquefaction sets in very slowly and shows itself by a slight pitting near the centre of each
colony. The deep colonies are not characteristic. Under a low power of the microscope the superficial colonies
have a granular and laminated appearance, and show at the spreading edge processes which are of the most
varied shapes, and which often form patterns of great delicacy and beaut}-.
Gelatine "stab" cultures.—The growth at the surface is like a superficial colony in gelatine plate culture.
The growth down the stab is not characteristic. Liquefaction slowly sets in at the surface, and eventually all
the delicate details of growth are lost.
Gelatine "streak " cultures.—The growth is like an elongated surface colony in plate culture. Briefly, a
white coarsely granular film forms on the sloping surface of the medium which peripherally shoots out processes
of very irregular shape. Liquefaction first shows itself as a longitudinal and central pitting of the bacterial film.
Gelatine "shake " cultures.—No bubbles of gas are formed.
Agar plate cultures.—The colonies are white in colour; they do not grow in the same characteristic way as
the colonies in gelatine plate culture.
Agar "stab" cultures.—Growth occurs all the way down the stab, and at the surface a greyish white-layer is
formed of irregular shape which resembles somewhat a surface colony in gelatine plate culture.
Agar "streak" cultures.—The growth extends over the surface of the medium as a greyish-white film. The
growth at the periphery in some measure simulates the corresponding growth on gelatine.
Potato cultures.—The growth is characteristic from a negative point of view as it is of a transparent
colourless character.
Broth cultures.—Grows slowly; a white bacterial deposit collects at the foot of the tube, leaving the
liquid above fairly clear.
Litmus milk cultures.—In milk at 20° C. No change is visible in three days. Later the milk turns slightly
acid, no clotting is visible even after one month.
Blood serum cultures.—At 20° C. a greyish-white, somewhat granular and film-like growth develops in a
few days. The edge is irregular. Apparently, no liquefaction takes place.
Indol reaction—No indol is formed in broth cultures, after 6 days incubation at 20° C.
Reduction of nitrates to nitrites.—No reduction takes place in 4 days at 20°. C. [Broth, 5 per cent., KNO3 0.1
per cent., water 94'9 per cent.]
Remarks.—This micro-organism has been compared with the descriptions of all the aerobic, motile,
non-chromogenic, liquefying bacteria, and it resembles none of them sufficiently closely to suggest identity. It
has been called B. Frondosus because the spreading edge of the colonies sometimes have a leafy appearance.
5.—Bacillus Fusiformis.
[An aerobic, non-chromogenic, motile, non-liquefying bacillus.]
Source.—London crude sewage: gelatine plate cultures heated to 80° C. for ten minutes.
Morphology.—Large bacilli, with rounded ends; solitary, in pairs, and in chains.
Motility.—Motile.
Spore formation.‡—Forms spores at the room temperature. These are large, and give a spindle-shaped
appearance to the cells.
Temperature.—No growth at 37° C. Grows slowly at the room temperature.
Gelatine plate cultures.—The growth is very slow. The surface colonies are circular, of an opaque porcelainwhite,
glistening appearance. The periphery is slightly transparent. By transmitted light the colonies are
yellowish in colour. In old cultures the white colour takes on a yellowish tint. The deep colonies are not
characteristic. Microscopically, under a low power, no delicate details of growth can be made out. No
liquefaction of the gelatine takes place.
Gelatine "stab" cultures.—Tardy growth, no liquefaction of the gelatine. A white growth appears along
the line of the stab, and on the surface a scanty yellowish-white layer very slowly develops.
Gelatine "streak" cultures.—A glistening porcelain-white layer is slowly formed, which is opaque, except at
the margins, which are slightly transparent. By transmitted light and by reflected light in old cultures a slight
yellowish tint may be seen. The growth does not extend far from the actual line of inoculation. No
liquefaction occurs.
Gelatine "shake" cultures.—No gas bubbles are formed.
Agar plate cultures.—The colonies arc white and more or less circular in shape; the growth is not
characteristic.
Agar "stab" cultures.—The growth is slow and imperfect. A whitish line appears along the line of the
stab, and on the surface a thin white layer slowly develops.
Agar "streak" cultures.—A thin whitish layer is slowly formed; the growth is not characteristic.
* See fig. 14, Plate IV.
† See fig. 15, Plate IV.
‡ See fig. 16, Plate IV.