AGf~ICULTURAL RESEARCH, PUSA.

PASTEURELLA GROUP 369
In septicaemic plague, thc bacillus can be demonstrated
and isolated by blood culture (vide p. 141).
DIAGNOSIS OF PLAGUE INFECTION IN WILD RATS
At autopsy the following appearances are noted :-enlargement
of lymphatic glamls, with pcriglanclular inflammation
and uedema, most frequently in tlle cervical glands owing to
the fad that the neck is thc common hal'bourage of Hcas ;
sel'lms effusion in the pleural en.vity; enlargement of tIl{'
spleen, 'which mny show small white nnclules in tIl(' pulp;
congestion and a mottlc'd appearance of the liver; congl'stion
and haelllorrhage lImIer the skin and in the internal organs.
Films arc prcparcd from the hcart blood, the glanfls and
spleen, and stained by Gram's method and with methylene
blue. Cultures should also be made, and the isolation of the
organism attempted by the usual methods. Guinea-pigs should
be inoculuted suhcutaneously with an emulsion of the splenic
tissue. In rats found dCllU of plague it may he r1il1lelllt to
demonstrate the bacilli microscopically or to isoj[Lte them in
011Itu1'c. earcases in a st.atc of liecomposition nmy he heavily COlltaminatc!l
with othcr organisms whielt l'cnder the miel'oseol>ic
cxamiu(ttion eon fusing and isolation dilllctllt.. InfectiOIl of
a white rat or guinea-pig, hy SIlle-firing the nasnl mucous
Jnclllbrane Or a shaved area of skin with materirtl [rom the
lesions, should be carried out.
PASTEURELLA GROUP
'rhe plague bacillus is only one speeies in a large biological
group (the Pasteurella group) which includes the organisms
of "haemorrhagic septicaemia" in various animals aIlcl B.
psetll[o-lulJerculosis ,·otlcntillllt. These orga.ni.sms :lud B. pestis
all show a similarity in morphology, staining reactions, cultural
and biochemical characters, but differ: in certain characters and
in their parasitism and virulence to different animal species.
Bacillus (lvisepi'icu8 (P. aviseptica) is the causative organism
of "fo'wI cholera" and septicaemia in certain birds. In
the blood the bacilli are present usually in considerable
numbers and show characteristic bipolar staining. Under
experimental conditions this organism is virulent to fowls,
pigeons and rabbits, but in guinea-pigs the i.nfection may
remain localised to the site of inoculation. (It may be not('d
here that Pasteur's classical work on attenuation of virulence
by continued cultivation for purposes of artificial immunisation
was carried out with this organism.)
Badllus 8uiseptict!8 (F. 8uiscpt'ica). The organism of swine
plague which takes thc form of !1 rapidly fatal septicaemia
2A.