NOT DESCRIBED IN PREVIOUS SECTIONS. 555 
coarse branches which ramify over the surface of the gelatin. A similar 
growth is observed upon the surface of gelatin stab cultures, and an abun- 
dant development takes place along the line of puncture. Upon nutrient 
agar a thick, opaque, slightly yellowish layer is formed. Upon potato a 
moist, shining, brownish layer is developed, and the potato acquires a 
brownish color. Upon blood serum the growth is less abundant than on 
agar; the blood serum is not liquefied. This bacillus grows rapidly at the 
room temperature; it is destroyed by a temperature of 80° C., and presum- 
ably does not form spores. 
Pathogenesis.—Recent cultures are very pathogenic for mice and for 
rabbits, less so for guinea-pigs. The subcutaneous injection of a small 
quantity of a pure culture kills susceptible animals in two or three days. 
More or less cedema is found at the point of inoculation. Injections into the 
rectum of rabbits gave rise to hemorrhagic enteritis, peritonitis, and death 
at the end of four days. 
BACILLUS A OF BOOKER. 
Obtained by Booker (1889) from the alvine discharges of children suffer- 
ing from cholera infantum. 
Morphology.—Bacilli with round ends, varying greatly in length, usually 
three to four 4 long and 0.7 u broad (in recent agarcultures). In older cul- 
tures the bacilli are shorter and smaller. 
Biological Characters.—An aérobic and facultative anaérobic, lique- 
JSying, motile bacillus. Grows at the room temperature in the usual culture 
media. In gelatin plates colonies are visible at the end of twenty-four 
hours; under the microscope these are nearly colorless, and liquefaction 
soon occurs around them. a gelatin stab cultures complete liquefaction 
occurs in three or four days. Upon agar a colorless layer covering the entire 
surface is developed in three or four days, and an abundant development 
occurs along the line of puncture. Agar colonies have a bluish look, and 
are surrounded by an indistinct halo which shades off gradually into the 
surrounding agar ; under a Jow power the colonies are light-brown and the 
borders indistinct; the surface has a delicate, wavy appearance. Upon po- 
tato the growth is luxuriant and of a dirty-brown color. Blood serum is 
liquefied by this bacillus. 2 : : 
Milk is coagulated into a gelatinous mass having an alkaline reaction; 
later the coagulum is dissolved. ee Ee 
Pathogenesis.—Mice and guinea-pigs fed with cultures in milk die in from 
one to eight days. 
BACILLUS ENDOCARDITIDIS GRISEUS. 
Obtained by Weichselbaum (1888) from the affected valves in a case of 
endocarditis recurrens ulcerosa. : 
Morphology.—Short rods with rounded or somewhat pointed ends, about 
two to three times as long as broad—of about the same dimensions as the 
bacillus of typhoid fever. 
Stains with the usual aniline colors and also by Gram’s method; the 
longer rods from old cultures are irregularly stained. _ : 
Biological Characters.—An aérobic, non-liquefying, motile bacillus. 
Refractive bodies may be seen in some of the rods, which resemble spores and 
are stained by the method of Ernst, but they do not show the resistance of 
known spores to physical and chemical agents. Grows well in the usual 
culture media at the room temperature. Upon gelatin plates colonies are 
formed which resemble those of Friedlinder’s bacillus, but which gradually 
acquire a gray or grayish-white color. The prominent, convex, superficial 
colonies under a low power are finely granular and grayish-brown in color; 
the deep colonies are yellowish-brown in color, have slightly notched_mar- 
gins, and the surface is covered with minute projections. In stab cultures 
