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. boviseptieus, Bac. suisepticiis, etc. 



Morphology and Biology of the Infective Agent. The 

 bacillus bipolaris septicus (Bac. multocida s. plurisepticus, 

 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, polymorphotis, 

 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 baeillus, the special 

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



Form. In the tissue fluids and stil] 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, diplocoeci; 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 hipolaris septicus. Fig. 24. Bacillus hipolaris septicus. 



Smear prepared from a fresh Smear from the blood of a chicken 



agar culture of the bacillus dead from fowl cholera. Polar 



of fowl cholera. Fuch- staining with fuchsin, and subse- 



sin staining. 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) fhey 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 



