516 BACILLI WHICH PRODUCE SEPTICAMIA 
BACILLUS CAVICIDA. 
Synonym.—Brieger’s bacillus. Probably a pathogenic variety of Bac- 
terium coli commune of Escherich. 
Obtained by Brieger (1884) from human feces. . ; 
Morphology.—Small bacilli, about twice as long as broad, which closely 
resemble the colon bacillus of Escherich (Bacterium coli commune). 
Biological Characters.—An aérobic (facultative anaérobic), non-liquefy- 
ing bacillus. ar we 
The growth in gelatin plate cultures is said to be very characteristic, the 
colonies being ‘‘in the form of very beautifully grouped, whitish, concentric 
rings, which are arranged like the scales upon the back of a turtle” (Hisen- 
berg). The writer has studied cultures of this bacillus brought from the 
bacteriological laboratories of Germany, side by side with cultures of the 
Bacterium coli commune of Escherich, and has found no appreciable differ- 
ences in the colonies in gelatin plates, or in the growth in various culture 
media. Upon potato it grows rapidly in the incubating oven, forming a 
dirty-yellow, moist layer. 
Pathogenesis.—This bacillus, as first obtained by Brieger, was character- 
ized by being very pathogenic for guinea-pigs, which were invariably killed, 
within seventy-two hours, by the subcutaneous injection of a minute quan- 
tity of a pure culture. The bacillus was found in great numbers in the 
blood of animals which succumbed to an experimental inoculation, The 
writer’s experiments with this bacillus, made in 1889, indicate that its patho- 
genic power had become attenuated, inasmuch as considerable quantities of 
a pure culture injected into guinea-pigs did not cause the death of the ani- 
mals—culture used came originally from Germany. Not pathogenic for 
rabbits or for mice. 
BACILLUS CAVICIDA HAVANIENSIS. 
This bacillus was obtained by the writer from the contents of the intestine 
of a yellow-fever cadaver, in Havana, 1889, through inoculated guinea-pigs. 
7 Morphology.—A bacillus with rounded ends, 
from two to three » long and about 0.7 » broad, 
frequently united in pairs. 
Stains readily with the ordinary aniline colors, 
Biological Characters.—-An aérobic and fac- 
ultative anaérobic, non-liquefying, actively mo- 
tile bacillus. 
In gelatin stab cultures the growth upon the 
surface is very scanty and thin, not extending far 
from the point of puncture ; along the line of 
uncture are developed small, translucent, pearl- 
ike, spherical colonies, which later become opaque 
s and sometimes granular. In gelatin roll tubes, 
Fic. 138.—Bacillus cavicida at the end of twenty-four hours at 22° C., 
Havaniensis; from « potato the deep colonies are very small spheres, of a pale 
culture. x 1,000. From apho- straw color; later they becomeopaque, light-brown 
tomicrograph. (Sternberg.) spheres, or may have a dark central mass sur- 
rounded by a transparent zone. The superficial 
colonies at the end of five days are small, translucent masses of a pale straw 
color towards the centre, with thin and irregular margins, sometimes with 
acentral light-brown nucleus; at the end of ten days the deep colonies are 
still quite small, of a brown color, and opaque. 
In glycerin-agar roll tubes, at the end of twenty-four hours, the deep colo- 
nies are in the form of a biconvex lens, and appear spherical when viewed 
in face and biconvex when seen from the side; they have a straw color 
