BACILLUS FALLAX 541 
0.6 micron in diameter and from 1.2 to microns in length. It is stated 
that the organisms are frequently somewhat curved. They are rarely 
found in short chains, and the usual method of occurrence is singly, 
although pairs of adherent bacilli are not uncommon. 
Weinberg and Seguin^ and Henry^ have demonstrated capsules 
surrounding individual bacilli which have been obtained either from 
pathological exudates or from experimental animals killed by the 
organism. 
Motility is observed in cultures obtained freshly from the animal 
body and in pathological exudates. The motion is undulatory and is 
readily observable. The flagellation is peritrichic. 
The organisms retain the stain by Gram's method both in young 
cultures and in material derived from the human or animal body. 
Older cultures, however, not only lose their ability to stain by Gram, 
they also become partially autolyzed and fail to stain distinctly even 
with ordinary dyes. 
Spores are formed, although not abundantly, in media not contain- 
ing utilizable carbohydrate but enriched with ascitic fluid, egg albumen 
or other nearly unaltered protein. The spores are slightly larger than 
the parent cell, and central or subterminal. 
Isolation and Culture.— Anaerobic agar cultures are not characteristic. 
The isolated colonies are round, somewhat opaque in the center, nearly 
transparent at the edge, which shows a distinct tendency to spread 
over the surface of the medium. Growth is distinctly stimulated by 
the addition of protein enrichment to the medium, as, for example 
ascitic fluid or blood serum. Milk is not peptonzied, but the casein is 
precipitated after a very few days by the accumulation of acid resulting 
from the action of the organism upon the lactose. After a few days a 
slow and moderate accumulation of gas is noticed in cultures developed 
in fermentation tubes. Gelatin is not liquefied, and the action upon 
this medium is very slight. 
Conditions of Growth.— The organism is an absolute anaerobe which 
grows best at 37° C. It is not fastidious in its requirement, but devel- 
ops best in media rich in protein or reinforced with utilizable carbo- 
hydrate. 
Products of Growth.— A slow evolution of gas is observed in glucose, 
maltose, saccharose and starch. Some strains also ferment glycerin 
with the production of gas. Both Henry and Weinberg and Seguin 
state that lactose is not fermented. Lactose is fermented by at least 
some strains, although more slowly than glucose or saccharose. The 
slow formation of gas in milk is in harmony with this observation. 
Mannitol, dulcitol, sorbitol, are not fermented. A faint, frequently 
transient evolution of gas bubbles takes place in meat meflia, and the 
reaction becomes slightly acid. There is no evidence of digestion in 
1 La Gangr6nc Gazeuse, Paris, 1917. 
= Jour. Pathol, and Bacteriol., 1916-1917, 21, 344. 
