History. Morphology and Biology 



79 



In the designation of the diseases belonging to this group the former appropiate 

 name of hemorrhagic septicemia will be used as it appears justifiable from a 

 pathological-anatomical standpoint. The causative agent is the species of bacteria 

 known as bacillus bipolaris septicus, while the various organisms of the group 

 causing this disease will be designated according to the species of animals affected, 

 viz., Bac. avisepticus, Bac. bovisepticus, Bae. suisepticus, etc. 



Morphology and Biology of the Infective Agent. Tlie 

 bacillus bipolaris septicus (Bac. multocida s. pliirisepticus, 

 Kitt; pasteurella, Lignieres, ovoid or girdle bacterium) mani- 

 fests the following characteristics without consideration of the 

 diseases belonging to this group or from what species of ani- 

 mals it originates (Lignieres). It is short, stains intensely 

 at the poles but only slightly in the middle, polymorphous, 

 non-motile, does not form spores, principally aerobic; does not 

 stain by Gram, grows in bouillon, gelatin and agar, but does 

 not grow on acid potatoes, nor liquefy gelatin, nor coagulate 

 milk; it does not produce indol in pancreatic bouillon, nor 

 redden Wirtz's agar; the bouillon cultures have a peculiar 

 characteristic odor. 



Besides these characteristics of the bipolar bacillus, the special 

 characteristics of the bacteria belonging to this group are the following : 



Form. In the tissue fluids and still more so in cultures the bacillus 

 represents a short rod about 1^ long, with rounded ends (Fig. 23). 

 It also occurs in the form of cocci, diplococci ; exceptionally also as 

 longer rods, threads and streptobacilli. Its dimensions vary according 

 to the origin of the disease in certain although not wide limits. 



Fig. 23. Bacillus bipolaris septicus. 



Smear prepared from a fresh 



agar culture of the bacillus 



of fowl cholera. Fuch- 



sin staining. 



Fig. 24. Bacillus bipolaris septicus. 

 Smear from the blood of a chicken 

 dead from fowl cholera. Polar 

 staining with fuchsin, and subse- 

 quent washing with a 1% 

 acetic acid. 



Staining. The bacilli stain quite readily with the aqueous aniline 

 dyes, and in the preparations made from the tissues or from the body 

 fluids (best in the blood of affected chickens) they appear stained only 

 at the poles, while the middle remains unstained (Fig. 24). These 

 results are obtained when the preparations are not stained too intensely 



