BACILLUS TERTIUS 543 
Bacillus tertius is a bacillus of varying length with rounded ends. Its 
diameter measures from 0.4 to 0.6 micron, and its length 4 to 8 microns. 
Very frequently the organism is more or less curved. In rapidly 
growing cultures the bacilli are single, or joined together in pairs; in 
older cultures filamentous forms are occasionally found. The motility 
is sluggish, and flagella, peritrichic in arrangement, Mere demonstrated 
by V. Hibler. Capsules have not been demonstrated. 
Young, actively growing cultures are Gram-positive, but older 
cultures and those which are not growing well fail to retain the Gram 
stain. Ordinary anilin dyes color the organism readily. 
Sporulation takes place readily in media free from utilizable carbo- 
hydrates. The spores are quite distinctive. They are strictly ter- 
minal, somewhat oval in outline, and while the diameter of the spore 
may vary somewhat with respect to the diameter of the parent cell, it 
always exceeds the latter when fully mature. Young, immature spores, 
although clearly discernible as enlargements of the ends of the bacillary 
cells, may in the earlier stages of development stain with ordinary 
anilin dyes. Fully mature, refractile spores, however, are resistant to 
staining, and require exposure to the intense dyes, as carbol-fuchsin, 
and vigorous steaming to color their substance. Once stained, however, 
they retain their color tenaciously. Usually young and mature spores 
are present in the same preparation, thus affording some differentiation 
from B. tetani, B. histolyticus and B. putrificus, which do not exhibit 
this peculiarity to any marked degree, although otherwise quite similar 
in morphology. 
Isolation and Culture.— Surface cultures upon agar are small, round, 
thin and transparent. Older cultures become somewhat more dense 
and less transparent. Submerged colonies are round or lenticular and 
not characteristic. 
Conditions of Growth. — B. tertius is an obligate anaerobe although 
less exacting in its requirement of the exclusion of molecular oxygen 
than some of the more delicate types. It grows readily at body temper- 
ature and the spores are fairly resistant to heat. 
Products of Growth. — Gelatin, coagulated serum and other proteins 
are not liquefied, and there is no evidence of the existence of a proteo- 
lytic enzyme. The cooked meat medium is slightly reddened during 
the earlier days of isolation, but the color fades after several days. 
There is no darkening of the meat. j\Iilk is coagulated, due to the 
accumulation of acid resulting from the fermentation of lactose. Some 
gas is formed, but slowly. The reaction becomes fairly acid. 
Acid and gas are formed in the hexoses— glucose, mannose, fructose, 
and galactose; in the bioses— maltose, lactose and saccharose. Manni- 
tol is also fermented by many strains. An occasional variant fails to 
ferment saccharose. Glycerin does not appear to be fermented nor 
is starch, inulin or salicin. The evolution of gas is not as vigorous as 
that characteristic of the gas bacillus (B. welchii). 
