CHAPTER III.
BACILLUS AEROGENES CAPSULATUS.

THIS very interesting micro-organism was first de-
scribed by Welch, and subsequently carefully studied by
Welch and Nuttall,1 and Welch and Plexner.2 It was
first secured from the body of a man dying suddenly of
aneurysm with a peculiar condition of gaseous emphy-
sema of the subcutaneous tissue and internal organs, and
a copious formation of gas in the veins and arteries.
The blood was thin and watery, of a lac-color, and
everywhere contained large and small gas-bubbles. The
blood-alteration was associated with a change in its
coloring-matter, which dissolved out of the corpuscles
and stained the tissues a deep red. The blood was found
to contain many bacilli, which were also obtained from
the various organs, especially in the neighborhood of the
gas-bubbles. The bacilli were in nearly pure culture.

The bacillus is a large organism, measuring 3-5 /* in
length, about the thickness of the anthrax bacillus, with
ends slightly rounded, or, when joined, square (Fig. 132).
It occurs chiefly in pairs and in irregular masses, but not
in chains, in this particular differing very markedly from
the anthrax bacillus. In culture-media the bacillus is
usually straight, with slightly rounded ends. In old
cultures the rods may be slightly bent, and involution-
forms occur. When several bacilli are joined together
the opposed ends are square-cut The bacillus varies
somewhat in size, especially in length, in different cul-
ture-media. It usually appears thicker and more vari-

1 Bull of the Johns Hopkins Hospital, July and Aug., 1892, vol. viii.,
No. 24.

2 Jour, of Exper. Med., vol. i., No. I, Jan., 1896,

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