§22 BACILLI WHICH PRODUCE SEPTICEMIA 
tion the capsule is so deeply stained that the bacillus is hidden; by careful 
treatment with a weak solution of acetic acid the capsule may be differen- 
tiated as a pale-red or violet envelope surrounding the deeply stained bacilli. 
Brologicat Characters.—An aer- 
obic aud facultative anaérobic, 
non -liquefying, non-motile bacillus. 
Spore formation not observed. 
Grows in the usual culture media 
at the room temperature. The cul- 
tures in agar or upon potato are very 
viscid and draw out into long 
threads when touched with the pla- 
tinum needle; the blood of an ani- 
mal killed by inoculation with this 
bacillus has the same viscid charac- 
ter. Upon gelatin plates minute 
colonies are first visible at the end 
of twenty-four to thirty-six hours; 
later the deep colonies are white, 
oval masses the size of a pin’s head; 
the superficial colonies attain the 
size of a lentil, and are flattened, 
hemispherical masses with a porce- 
Fie 141.—Bacillus capsulatus, from peritoneal Jain-white color. In gelatin stab 
exudate of an inoculated guinea-pig. x 1,000. exyltures growth occurs to the bot- 
From a photomicrograph. (Ffeiffer.) tom of the line of puncture, and on 
the surface a shining white, circular, 
arched mass forms around the point of puncture, resembling the growth of 
Friedlander’s bacillus. Upon the surface of agar, at 37° C, at the end of 
twenty-four hours a thick, soft layer of a pure white color is formed, which 
is very viscid and resembles the growth of Micrococcus tetragenus upon the 
same medium. Upon potato an abundant and viscid, shining, yellowish- 
white layer is quickly developed. 
Pathogenesis.—Pathogenic for white mice and for house mice, which die 
at the end of two or three days after being inoculated at the root of the tail 
with a small quantity of a pure culture. Inoculation from mouse to mouse 
increases the virulence of the cultures. At the autopsy the superficial veins 
are distended with blood, the inguinal glands enlarged, the spleen consid- 
erably enlarged, the liver and kidneys hyperemic, the intestine pale, the 
heart distended with blood, which usually is very viscid and is drawn out 
into threads when touched with the platinum needle. The bacilli are found 
in the blood and in all of the organs, in the contents of the peritoneum and 
pleuree, and in the exudate in the vicinity of the point of inoculation. 
Pathogenic also for guinea pigs and for pigeons; guinea-pigs are infallibly 
killed within thirty-six hours by the injection of a single drop of a bouillon 
culture, twenty-four hours old, into the cavity of the abdomen; the blood 
contains the bacillus in enormous numbers, as does the viscid fluid found in 
the peritoneal cavity. Rabbits do not succumb to intraperitoneal or subcu- 
taneous inoculations, but are killed by the intravenous injection of one 
cubic centimetre of a recent bouillon culture. Putrefactive changes occur 
very quickly in animals killed by inoculation with this bacillus. 
BACILLUS HYDROPHILUS FUSCUS. 
Obtained by Sanarelli (1891) from the lymph of frogs suffering from a 
fatal infectious disease. 
Mor phology.—Bacilli with rounded ends, usually from 1 to 3 « in length; 
often short oval; may grow out into filaments of 12 to 20 # in length. 
_ Biological Characters.—An aérobic, liquefying, motile bacillus. Grows 
in the usual culture media at the room temperature. In gelatin stab cul- 
