NOT DESCRIBED IN PREVIOUS SECTIONS. 565 
bacillus from infected rats to man, or from one individual to another. 
Infection in man occurs by inoculation through lesions of the skin 
and also by the respiratory passages (pulmonic form). 
BACILLUS PISCICIDUS AGILIS (Sieber). 
Discovered by Sieber (1895) in infected fish, which died of an epidemic 
disease in the laboratory of Professor Nencki, at St. Petersburg. 
Morphology.—Short bacilli, often united in pairs. 
Biological Characters.—An aérobic and facultative anaérobic, motile, 
liquefying bacillus. In old cultures in bouillon spores are developed. 
Grows at temperatures of from 12° to 37.5° C. Thermal death point, 60° to 
65° C. On gelatin and agar plates forms granular, grayish, or yellowish 
colonies, which appear to be made up of three concentric rings—the outer one 
having a jagged outline. Gasis developed during the growth of the bacillus 
—carbon dioxide and methy] merecaptan in small amount. Upon potato it 
forms yellowish-brown, pearl-like colonies. Causes coagulation of milk. 
Retains its vitality and virulence for months in well or river water. 
Pathogenesis.—Pathogenic for fish, frogs, guinea-pigs, rabbits, mice, 
and dogs (not for birds). Old cultures are more pathogenic than recent 
ones, and gelatin cultures are the most active. Frogs are killed in half an 
hour by 0.1 cubic centimetre of a bouillon culture six days old. Filtered 
cultures are as toxic as those containing the living bacillus; they give with 
iron chloride a characteristic color reaction—an intense red color. Sieber 
has obtained from his cultures an extremely toxic alkaloid in the form of a 
hydrochlorate. Two litres of filtered culture gave 0.1 gramme of this salt. 
An aqueous solution of this killed a frog in fifteen minutes in the dose of 
0.0035 gramme. 
BACILLUS OF MERFSHKOWSKY. 
Obtained by Mereshkowsky (1894) from infected animals (Spermophilus 
musicus) which died from an epidemic malady developed in his laboratory. 
Morphology.—Closely resembles Loffler’s Bacillus typhi murium. 
Biological Characters.—An aérobic, motile, uon-liquefying bacillus. 
Spore formation not observed. Grows in the usual culture media at the 
room temperature —best at 37.5° C. In bouillon, at the end of twenty-four 
hours, the medium is clouded aud a white pellicle is seen upon the surface, 
which breaks up into small flocculi and falls to the bottom when the tube 
is slightly shaken. On gelatin plates minute, slightly granular, pale-brown 
colonies may be seen, under a low power at the end of twenty-four hours; 
on the second day these are visible as white spheres, which under the micro- 
scope have a pale-brown color and a more or less transparent, peripheral 
zone. In media containing glucose no gas is developed. The growth upon 
agar and potato presents nothing characteristic. ; : 
Pathogenesis.—Pathogenic for Zieselmausen (Spermophilus musicus), 
for Spermophilus guttatus, for squirrels (Sciurus vulgaris) for house mice, 
for field mice (Arvicola arvalis). Not pathogenic for man or forthe domes- 
tic animals tested, horse, swine, sheep, fowls. Mereshkowsky proposes to 
use cultures of this bacillus for the extermination of field mice, which die in 
from one to ten days after being fed upon biscuit wet with a bouillon cul- 
ture. 
BACILLUS OF EMMERICH AND WEIBEL. 
Obtained by Emmerich and Weibel (1894) from infected trout in ponds 
belonging to an establishment for raising these fish. The disease appeared 
as a superficial ‘‘furunculosis with secondary development of abscesses con- 
taining bloody pus.” Death occurred in from twelve to twenty days. The 
pustules and secondary abscesses and blood from the heart and various or- 
gans contained bacilli, which proved to be the cause of the infectious malady. 
