BUBONIC PLAGUE. 435

1. Plague with buboes. -

2. Plague without buboes, but with a primary specific
pneumonia in which the bacilli occur in immense num-
bers in the affected pulmonary tissue, but sparingly in the
blood and kidney.

The studies of Kitasato and Yersin show that in blood
drawn from the finger-tips and in the softened contents
of the glands a small bacillus is demonstrable. The
organisms are small, stain much more distinctly at the
ends than in the middle, so that they resemble diplo-
cocci, and in fresh specimens seem to be surrounded by
a capsule. Kitasato compares the organism to the well-
known bacillus of ckicken-cholera. It is feebly motile
(according to Abel, entirely non-motile), and does not
seem to form spores. Nothing is said in the original
descriptions about the presence of flagella, though it is
probable from the studies of Gordon l that some, at least,
of the bacilli may be possessed of them. It does not
stain by Gram's method.

When cultures are made from the softened contents of
the buboes the bacillus may be obtained almost or quite
pure, and is found to develop upon artificial culture-
media. In bouillon a diffuse cloudiness results from
the growth, as observed by Kitasato, though in Yersin's
observations the culture more nearly resembled erysipe-
las cocci, and contained zooglea attached to the sides and
at the bottom of the tube of nearly clear fluid.

According to Haffkine,2 when an inoculated bouillon
culture is allowed to stand, perfectly at rest, on a solid
shelf or table a characteristic appearance results. In
from twenty-four to forty-eight hours, the liquid remain-
ing limpid, flakes appear underneath the surface, forming
little islands of growth, which in the next twenty-four
to forty-eight hours grow down into a long stalactite-like
jungle, the liquid always remaining clear. In four to

1 Centralbl. f. Bakt. u. Parasitenk., Sept. 6, 1897, Bd. xxii., Nos. 6 and 7,
p. 170.

2 Brit, Med. Joztr., June 12, 1897, p. 1461.