538 



PATHOGENIC AEROBIC BACILLI 



.slightly iridescent; the deep colonies are spherical, opaque, and homo- 

 geneous. 



The growth upon the surface of nutrient agar is abundant and rapid, of 

 a shining milk-white color, and cream-like in consistence. An abundant 

 development forms alon^ the line of puncture and the culture medium is 

 split up by gas bubbles. In glycerin-agar the evolution of gas is very abun- 

 dant and the culture medium acquires an intensely acid reaction. 



On potato the growth is abundant and rapid at a temperature of 20 to 

 30 C., forming a thick, semi-fluid mass of a milk-white color. 



I have not obtained any evidence that this bacillus forms spores; the 

 cultures are sterilized by ten minutes' exposure to a temperature of 160 F. 



When cultivated in bouillon to which five per cent of glycerin has been 

 added the culture medium acquires a milky opacity, and there is a copious 

 precipitate, of a viscid consistence, consisting of bacilli ; during the period 

 of active development the surface is covered with gas bubbles, as in a sac- 

 charine liquid undergoing alcoholic fermentation, and the liquid has a de- 

 cidedly acid reaction. 



Pathogenesis. Pathogenic for rabbits and for guinea pigs when injected 

 into the cavity of the abdomen one to two cubic centimetres of a culture in 

 bouillon. The animal usually dies in less than twenty-four hours. The 

 bacilli are found in the blood in rather small numbers, and are frequently 

 seen in the interior of the leucocytes. The spleen is enlarged, the liver 

 normal, the intestine usually hyperaemic. 



BACILLUS CUNICULICIDA HAVANIENSIS. 



Obtained by the writer (1889) from the contents of the intestine of yellow- 

 fever cadavers, and also from fragments of yellow-fever liver preserved for 



forty-eight hours in an antiseptic wrap- 

 pingmy bacillus x, Havana, 1889. 



Morphology. This bacillus resembles 

 the colon bacillus in form, but is some- 

 what larger, from 2 to 4 // in length and 

 from 0.8 to 1 JJ> in diameter ; sometimes 

 associated in pairs ; may grow out into 

 short filaments not common. The ends 

 of the rods are rounded, and under cer- 

 tain circumstances vacuoles are seen at 

 the extremities, especially in potato cul- 

 tures. 



Stains quickly with the aniline colors 

 usually employed, and also by Gram's 

 method. 



Biological Characters. An aerobic 

 and facultative anaerobic, non-lique- 

 fying bacillus. Under certain circum- 

 stances may exhibit active movements, 

 but is usually motionless. 



A very curious thing with reference 

 to this bacillus is that it presented ac- 

 tive movements in my cultures made directly from yellow-fever cadavers, 

 but that these movements were not constant, and that since my return to 

 Baltimore I have not, as a rule, observed active movements in cultures from 

 the same stock, which, however, preserved their pathogenic power and other 

 characters. In Havana these movements were usually not observed in all 

 the bacilli in a field under observation, but one and another would start from 

 a quiescent condition on an active and erratic course ; sometimes spinning 

 actively upon its axis, and again shooting across the field as if propelled by 

 a nagellum. 



FIG. 150. Bacillus cuniculicida Havani- 

 ensis, from a single colony in nutrient gela- 

 tin, x 1,000. From a photomicrograph. 

 (Sternberg.) 



