536 THE ANAEROBIC BACTERIA 
Morphology.— Vibrion septique is a rather thin, rod-shaped baciUiis 
with. rounded ends, measuring from 0.6 to 1 micron in diameter and 
from 2 to 8 microns in length. Usually, however, the organism is less 
than 5 microns long. It tends to form chains, particularly in the animal 
or human body. Such chains are readily demonstrated by impression 
smears made from the surface of parenchymatous organs. The addi- 
tion of serous fluids or fresh tissue to culture media, as well as growth 
in the animal body, or even upon coagulated blood serum, appears to 
induce involution formation. The organisms thus altered are rather 
striking in appearance and quite characteristic and distinctive. These 
aberrant forms are either recognizable as bulbar enlargements upon 
the ends of rods, or occur as spindle-shaped deformities with contracted 
ends, resembling a lemon in outline. Such involution forms have been 
referred to as "navicular" or "citron" types. ^ The observance of these 
involution forms in smears from human or animal sources is very 
suggestive of the identity of the organism. Their absence, however, 
is not exclusive of a diagnosis of the presence of Vibrion septique. 
Motility is observed, both in artificial cultivations and in material 
from the body. The motion is flexuous and serpentine in anaerobic 
media. The addition of serum or tissue fluids accentuates the motion. 
There are numerous peritrichic flagella. 
The organism retains the Gram stain, especially in young cultures. 
Older growths may lose their ability to retain the Gram stain. Ordi- 
nary anilin dyes color the Vibrion readily. Capsules have not been 
demonstrated. 
Sporulation occurs readily, both in exudates recovered from the 
body and in artificial cultivations under definite conditions. Appa- 
rently the presence of tissue or tissue fluids promotes sporulation, but 
spores rarely or never occur in the living body. The spores are central 
or subterminal, somewhat larger than the diameter of the vegetative 
cell, and oval in outline. 
At the time of sporulation, which frequently begins within twenty- 
four to forty-eight hours after inoculation, the organisms become 
swollen, giving rise not only to spores but also to the navicular or citron 
forms mentioned above. There is no evidence that these irregularly 
staining involution forms are related, except in association with the 
time of their occurrence, to the process of normal sporulation. Sporu- 
lation is not observed, as a rule, in media containing utilizable carbo- 
hydrate. 
Isolation and Cultures.— Vibrion septique is an obligate anaerobe. 
Growth is most luxuriant in media containing fresh tissue or those 
enriched with serous fluids. Ordinary media containing liver or brain, 
however, are usually productive of active cultures. From material 
containing other organisms, as well as Vibrion septique, inoculation 
into guinea-pigs and isolation from the blood stream remote from the 
1 Robertson: British Med. Jour., 1918, i, 583. 
