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 oedema is found at the point of inoculation. Injections into the 

 rectum of rabbits gave rise to haemorrhagic 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 // long and 0.7 /* broad (in recent agar cultures). In older cul- 

 tures the bacilli are shorter and smaller. 



Biological Characters. An aerobic and facultative anaerobic, lique- 

 fying, 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. In 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 low 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. 



Milk is coagulated into a gelatinous mass having an alkaline reaction ; 

 later the coagulum is dissolved. 



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 aerobic, 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 Friedlander'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 



