BACILLUS MALLEI 131 



colour and denser in consistency, until it finally presents a reddish-brown 

 colour and the surrounding surface of the potato becomes darkened. 

 According to Semner, the Bacillus mallei exhibits unusual pleomorphism 

 on potatoes, often forming long felt-like interlaced filaments, not unlike 

 the threads of the Bacillus anthracis, and, finally, blebby and club-like 

 swellings. 



In Bouillon a diffuse clouding takes place, a tenacious, ropy sediment 

 being ultimately formed. 



In Milk Media to which a little litmus is added, the blue colour 

 becomes reddish in four or five days, and quite red in two weeks at 

 37 C., the milk being finally separated into a firm clot of casein and 

 clear whey. 



Vitality. Cultures of the Bacillus mallei lose their virulence very 

 quickly by a natural weakening as early as the fourth and fifth genera- 

 tions ; therefore to retain the cultures virulent it is necessary after two 

 or three culture generations to pass the virus through a susceptible 

 animal. According to Loffler the Bacillus mallei lives three months in 

 a dry condition, while other authors find that when spread out in a thin 

 layer the bacilli die in ten days. When exposed to heat they are killed 

 at 1 00 C. in two minutes, and at 80 C. in five minutes. Exposed to 

 the action of corrosive sublimate 1 to 1000 they are killed in fifteen 

 minutes, and in 5 per cent, carbolic acid in one hour ; and they also 

 lose their virulence quickly in distilled water (six days). The virulence 

 is not destroyed by putrefaction ; inoculations made with central por- 

 tions of glanders lungs, exposed to the air for fifteen, eighteen, and 

 twenty-six days, have given positive results. 



Pathogenesis. The ass, mule, horse, goat, cat, sheep, dog, pig, and 

 mankind, are susceptible. Cattle are immune. 



Among laboratory animals, the field mouse, wood mouse, and the 

 guinea-pig are the most susceptible, the rabbit being less so; white 

 mice and house mice are immune. Birds, with the exception of the 

 pigeon, are refractory. 



Field mice inoculated subcutaneously with a small quantity of a culture 

 die very quickly in three or four days. The spleen is found enlarged 

 and generally studded with minute grey nodules, which are rarely present 

 in the lungs, but frequently found in the liver. Pure cultures can be 

 obtained from these nodules. The characteristic lesions are much more 

 marked in the guinea-pig, which lives from six to eight weeks after 

 inoculation. The specific inflammatory condition of the mucous mem- 

 brane of the nostrils is almost always present ; the joints are infiltrated 

 and swollen. Orchitis and epididymitis are present in male animals, 

 while the internal organs, lungs, kidneys, spleen and liver are generally 

 the seat of the characteristic nodular formations. Pure cultures can be 

 obtained from the diseased centres. 



