222 BACILLI OF THE HEMORRHAGIC SEPTICEMIA GROUP 



(inflammation of the intestines), and sometimes an acute serous 

 pneumonia is also present. According to Ward the most striking 

 intestinal lesions are found deeply in the first and second duodenal 

 flexures. The mucosa is deeply reddened and studded with hemor- 

 rhages, varying in size, but seldom exceeding one millimeter in 

 diameter. These hemorrhages involve the intestinal coats to such an 

 extent that they are distinctly visible on the peritoneal surface. The 

 contents of the duodenum consist of a pasty mass more or less 

 thickly intermingled with blood clots. Marked lesions are very rarely 

 observed in other portions of the intestines. In cases where these 

 morbid changes are not so well marked, diagnosis with the naked 

 eye is impossible, and the blood must be examined microscopically 

 and other birds inoculated. 



Morphology and Staining Properties. The organism causing fowl 

 cholera is now generally known as the Bacillus avisepticus (Latin, 

 avisepticus, septic for birds). It is one of the smallest of the group and 

 is rarely longer than one micron. The bacilli are frequently seen in 

 the blood as round or oval bodies; they stain with the ordinary watery 

 anilin stains in a polar manner, and can be easily mistaken for diplo- 

 cocci. They are Gram negative, immobile, possess no flagella, and 

 form no spores. Enormous numbers are present in the blood of sick 

 and dead birds. The diagnosis from the blood must be made either 

 before or shortly after death, because putrefaction bacteria closely 

 resembling the Bacillus avisepticus frequently develop in cadavers of 

 birds. 



Cultural Properties. In a gelatin stick culture made from the blood of 

 a bird and kept at room temperature, densely crowded, small, translu- 

 cent whitish points appear after a few days along the line in the gelatin. 

 These, later, become confluent and form a white filiform mass. On 

 the surface, small, delicate, transparent dewdrop-like colonies appear, 

 and later become more decidedly white. The gelatin does not become 

 liquefied. On agar slants the development is similar but quite scanty, 

 and the colonies generally do not become confluent but remain small. 

 The growth on blood serum is generally more abundant, and leads to 

 a thin, dull white film over the entire surface. The organism generally 

 does not grow on potatoes. The growth in nutrient bouillon is abun- 

 dant. It produces clouding of the medium, a sediment at the bottom 

 of the tube, and sometimes a thin, delicate pellicle on the surface. 



Susceptible Animals. If chickens, geese, ducks, pigeons, turkeys, 

 sparrows, etc., are inoculated subcutaneously with a minimum amount 

 from cultures of the Bacillus avisepticus, they develop a rapidly fatal 

 hemorrhagic septicemia. Rabbits and mice are also quite susceptible, 

 and succumb to the infection. Cattle, sheep, and horses, after sub- 

 cutaneous infection, develop local abscesses containing numerous 

 bacteria, but there is no general infection. Guinea-pigs, after sub- 

 cutaneous inoculation, develop a local abscess only, but after an 

 intraperitoneal application die from a septic peritonitis. Repeated 



