BACILLUS (EDEMATIENS 547 
anaerobic group in this respect. Also, the colonies are very delicate 
and tend to grow as a fine film upon the surface of solid media. Tf the 
surface of the medium is dry, the colonies appear in from two to three 
days as rather large (2 to 4 mm.) somewhat transj)arent irregidar 
growths, frequently with denser centers. Adjacent colonies tend to 
become confluent. The isolation is attended with material difficulties, 
therefore, when it is growing in association with other anaerobes. It 
has been found ad^'antageous to allow sporulation to take place, when 
time permits, and to heat the material to 100° C. for five minutes prior 
to plating. The isolation of single spores with the modified Barber 
technique rarely fails to produce pure cultures if the precaution is taken 
of carefully excluding oxygen from the medium into which the spore is 
inoculated. 
Products of Growth.— Weinberg and Seguin state that only gelatin 
containing 2 per cent of glucose is liquefied; many cultures, however, 
liquefy the gelatin without the addition of glucose, after the organisms 
have become acclimatized to artificial media. A soluble gelatin liquefy- 
ing enzyme very sensitive to oxygen can be obtained, which will induce 
liquefaction in either plain or glucose gelatin. The enzyme is most 
abundant or most active about the third day of cultivation and it 
appears in plain gelatin cultures provided the conditions of anaero- 
biosis are carefully maintained. Milk is not altered in appearance but 
a slight initial acidity is demonstrable, which soon (three days) recedes 
almost to the original reaction. The casein is not altered, at least dur- 
ing the first ten days of culti\'ation. Gas and acid are produced in 
glucose, maltose and levulose broths. Henry^ states that xylose and 
starch are also fermented. Other carbohydrates are apparently not 
utilized. 
Meat medium is not appreciably darkened. A few gas bubbles 
appear during the earlier period of incubation but little odor is de\'el- 
oped. A faint pink tinge may or may not be imparted to the medium. 
Toxin Formation.— INIany strains of B. oedematiens form a soluble 
poison, which, like that of Vibrion septique and B. welchii, appears in 
the first day or two of active growth. Even in amounts as small as 
0.05 cc, it will kill laboratory animals. It is stated that less than a 
cubic centimeter of such a toxin will kill a horse. Guinea-pigs injected 
with a fatal dose of toxin die within forty-eight hours, as a rule, but 
death may occur within six hours. The intramuscular introduction of 
the toxin leads to a gelatinous edema, but there is much less necrosis 
with this toxin than with that produced by the Welch bacillus. 
An antitoxin of considerable potency has been prepared by carefully 
immunizing horses with graduated amounts of toxin. 
Pathogenesis. — The injection of whole cultures of B. (I'dematiens 
into experimental animals, which leads to a fatal result, causes not 
only an extensive gelatinous edema, principally of muscular structures, 
1 Jour. Pathol, and Bacteriol., 191&-1917, 21, 344. 
