Page 346 - My FlipBook

318 THE MICRO-OEGANISMS OF THE HUMAN MOUTH.

arc wanting. Growth on agar-agar and on potato like that of
Bacterium aerogenes I, hut somewhat more yellowish and less
moist; growth without oxygen hut little retarded.
Helicobacterium aeroyenes. Thin motile rods, single or in
chains; grows into long undulating threads which sometimes
it develops transparent white or but slightly
form Spiruliuae ;
colored colonies, whose composition of rods and threads is per-
ceptible even under 150 diameters. The colonies are round,
oval, snail-, spindle-, or spiral-shaped, in short, show almost every
possible form. In puncture-cultures the bacterium grows evenly
along the line of puncture with a light yellowish color, and
covers the surface after forty-eight hours (though not invariably)
with a thin, hardly visible, bluish, dry layer. In line-cultures it
also forms a thin, broad growth with very rugged margins ; by
transmitted light the culture has a flaky or crystalline appear-
ance. Growth on agar-agar not characteristic ; grows slowly on
potatoes; has an indented margin, dry surface, yellowish-brown
(mauve) color; growth without air restricted.
Bacillus aerogenes. Kather small, motile rods of various
lengths ; forms completely round, homogeneous, transparent,
white or slightly yellowish colonies. Older colonies occasionally
show a series of concentric rings. In line-cultures it grows
evenly along the line of inoculation; is of yellowish color; on
the surface it forms a thin, pearl-gray deposit with indented
margin; does not liquefy; in older cultures the line of inocu-
lation is dark brown, and surrounded by a peculiar light brow^n
lialo growth on agar-agar shows nothing remarkable ; on potato
;
it grows very slowly, forming a dry deposit of bluish-yellow dirty
color and irregular margin ; growth without air very limited.
Bacterium aerogenes II. Morphologically indistinguishable
from Bacterium aerogenes I; on agar-agar, potatoes, and in
line-cultures it shows a growth similar to the former. The
colonies, however, display essential differences : they are com-
pletely round, distinctly defined, yellowish, and, where they are
closely gathered, completely homogeneous; where far apart, they
show one or many black, irregular fissures on the surface;
growth without air very limited ; but few air-bubbles form under
mica. A very slow liquefaction of the gelatine takes place,
forming a funnel (but only after a number of days).