IN SUSCEPTIBLE ANIMALS. 455 



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. 



Biotogical Characters. An aer- 

 obic and facultative anaerobic, 

 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- 

 lain white color. In gelatin stick Fia 143 -~ Bacillus capsulatus, from peritoneal 

 Cultures growth occurs to the bot- exudate of an inoculated guinea-pig, x 1,000. 

 torn of the line of puncture, and on ^* a photomicrograph. (Ffeiffer.) 

 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 hyperaemic, 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 

 pleurae, 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. 



81. BACILLUS HYDROPHILTJS FUSCUS. 



Obtained by Sanarelli (1891) from the lymph of frogs suffering from a 

 fatal infectious disease. 



Morphology. Bacilli with rounded ends, usually from 1 to 3 H in length; 

 often short oval; may grow out into filaments of 12 to 20 jit in length. 



Biological Characters. An aerobic, liquefying, motile bacillus. Grows 

 in the usual culture media at the room temperature. In gelatin stick cul- 



