NOT DESCRIBED IN PREVIOUS SECTIONS. 557 
from which other similar outgrowths occur ; the branching outgrowths may 
anastomose. The gelatin is liquefied in the vicinity of these lines of growth, 
forming a network of channels. A similar growth is seen upon the surface 
of gelatin stab cultures, and along the line of puncture white, irregular 
masses are formed, from which rather coarse branches are given off which 
often have a club-shaped extremity. In older cultures the finer branches 
disappear, so that the secondary centres of growth are disconnected from the 
original colonies; complete liquefaction of the gelatin occurs in about two 
weeks; the liquefied gelatin has a yellowish color and peculiar odor. Upon 
the surface of nutrient agar, at 37° C., a white layer isformed. Upon potato 
the development is slow and results in the formation of a dry, yellowish 
layer. In milk coagulation first occurs, and the coagulum is subsequently 
dissolved; a slightly acid reaction is produced. This bacillus grows best in 
the incubating oven at 37°, and does not develop at temperatures below 16° 
C. The spores require for their destruction a temperature of 100° C. main- 
tained for four minutes (determined by the writer, 1887). 
Pathogenesis. —The introduction of pure cultures of this bacillus into 
hives occupied by healthy swarms causes them to become infected with foul 
brood; grown bees also become infected when given food containing the ba- 
cillus (Cheshire). Mice injected subcutaneously with a considerable quan- 
tity die within Liskin ae hours, guinea-pigs in six days (Hisenberg). 
Smell amounts injected beneath the skin of mice or rabbits produce no appa- 
rent result. 
BACILLUS OF ACNE CONTAGIOSA OF HORSES. 
Obtained by Dieckerhoff and Grawitz (1885) from pus and dried scales 
from the pustules of ‘‘ acne contagiosa ” of horses. 
Morphology.—Short rods, straight or slightly bent, 0.2 ~ in diameter. 
Stains best with an aqueous solution of fuchsin, and also by Gram’s 
method; does not stain well with Léffler’s alkaline solution of methylene 
blue. 
Biological Characters.—An aérobic, non-liquefying bacillus. In gelatin 
stab cultures a very scanty growth occurs along the line of puncture; upon 
the surface a white mass forms about the point of puncture. Upon blood 
serum and nutrient agar an abundant growth at the end of twenty-four 
hours at 37° C., consisting of white colonies along the impfstrich, which 
later have a yellowish-gray color. The growth is more abundant and rapid 
upon blood serum than upon other media. — . ; ; 
Pathogenesis. —Pure cultures of the bacillus described are said by Diecker- 
hoff and Grawitz to produce typical acne pustules when rubbed into theskin 
of horses, calves, sheep, and dogs. When rubbed into the intact skin of 
guinea-pigs a phlegmonous erysipelatous inflammation was produced, and 
the animal died at the end of forty-eight hours with symptoms of toxsemia. 
Subcutaneous injections in guinea-pigs caused toxzemia and death at theend 
of twenty-four hours. At the autopsy a hemorrhagic infiltration of the in- 
testinal mucous membrane was observed; the bacilli were not found in the 
internal organs. In rabbits pure cultures rubbed into the intact skin caused 
a development of pustules and a severe inflammation of the subcutaneous 
connective tissue, from which the animal usually recovered. Subcutaneous 
injections in rabbits sometimes caused a fatal toxemia. House mice, field 
mice, and white mice were not affected by the application of cultures, by 
rubbing, to the uninjured skin, but succumbed to subcutaneous injections in 
twenty-four hours or between the fifth and tenth days. Those which died’ 
at a late date presented the pathological appearances which characterize 
pyzmia. 
