516 



BACILLI WHICH PRODUCE SEPTICAEMIA 



BACILLUS CAVICIDA. 



Synonym. Brieger's bacillus. Probably a pathogenic variety of Bac- 

 terium coli commune of Escherich. 



Obtained by Brieger (1884) from human faeces. 



Morphology. Small bacilli, about twice as long as broad, which closely 

 resemble the colon bacillus of Escherich (Bacterium coli commune). 



Biological Characters. An aerobic (facultative anaerobic), non-liquefy- 

 ing bacillus. 



The growth in gelatin plate cultures is said to be very characteristic, the 

 colonies being " in the form of very beautifully grouped, whitish, concentric 

 rings, which are arranged like the ccales upon the back of a turtle " (Eisen- 

 berg). The writer has studied cultures of this bacillus brought from the 

 bacteriological laboratories of Germany, side by side with cultures of the 

 Bacterium coli commune of Escherich, and has found no appreciable differ- 

 ences in the colonies in gelatin plates, or in the growth in various culture 

 media. Upon potato it grows rapidly in the incubating oven, forming a 

 dirty-yellow, moist layer. 



Pathogenesis. This bacillus, as first obtained by Brieger, was character- 

 ized by being very pathogenic for guinea-pigs, which were invariably killed, 

 within seventy- two hours, by the subcutaneous injection of a minute quan- 

 tity of a pure culture. The bacillus was found in great numbers in the 

 blood of animals which succumbed to an experimental inoculation. The 

 writer's experiments with this bacillus, made in 1889, indicate that its patho- 

 genic power had become attenuated, inasmuch as considerable quantities of 

 a pure culture injected into guinea-pigs did not cause the death of the ani- 

 mals culture used came originally from Germany. Not pathogenic for 

 rabbits or for mice. 



BACILLUS CAVICIDA HAVANIENSIS. 



This bacillus was obtained by the writer from the contents of the intestine 

 of a yellow-fever cadaver, in Havana, 1889, through inoculated guinea-pigs. 



Morphology. A bacillus with rounded ends, 

 from two to three u long and about 0.7 p- broad, 

 frequently united in pairs. 



Stains readily with the ordinary aniline colors. 

 Biological Characters. An aerobic and fac- 

 ultative anaerobic, non -liquefying, actively mo- 

 tile bacillus. 



In gelatin stab cultures the growth upon the 

 surface is very scanty and thin, not extending far 

 from the point of puncture ; along the line of 

 puncture are developed small, translucent, pearl- 

 like, spherical colonies, which later become opaque 

 and sometimes granular. In gelatin roll tubes, 

 at the end of twenty- four hours at 22 C., 

 the deep colonies are very small spheres, of a pale 

 stra w color ; later they become opaque, light-brown 

 spheres, or may have a dark central mass sur- 

 rounded by a transparent zone. The superficial 



colonies at the end of five days are small, translucent masses of a pale straw 

 color towards the centre, with thin and irregular margins, sometimes with 

 a central light-brown nucleus ; at the end of ten days the deep colonies are 

 still quite small, of a brown color, and opaque. 



In gtycerin-agar roll tubes, at the end of twenty-four hours, the deep colo- 

 nies are in the form of a biconvex lens, and appear spherical when viewed 

 in face and biconvex when seen from the side ; they have a straw color 



FIG. 138. Bacillus cavicida 

 Havaniensis; from a potato 

 culture. X 1,000. From a pho- 

 tomicrograph. (Sternberg.) 



