22 HOG CHOLEBA 



many healthy swine. In the absence of knowledge 

 of the filterable hog cholera virus, all these investi- 

 gators were inclined to regard the organism as the 

 cause of epizootic swine plague, and to ascribe 

 repeated failures in causing it to produce trans- 

 missible disease, to the fact that field conditions 

 could not be duplicated in the laboratory. 



The organism is rod-shaped varying in length 

 from .8 to 2 microns, and in width from .4 to 1.2 

 microns. Often the ends are rounded giving it 

 an oval shape, but it is not uncommon for the rods 

 to be so short as to resemble micrococci. Some- 

 times involution forms are observed. In cover- 

 glass preparations made direct from the tissues 

 and stained with basic aniline dyes, Bact. suisepti- 

 cum often stains heavily at the ends and around 

 the periphery, and very lightly or not at all in the 

 center. Preparations made from cultures do not 

 as a rule exhibit this bipolar staining. 



The organism is subject to wide variation in 

 virulence. Babbits, mice and guinea-pigs readily 

 succumb to injections of minute quantities of cul- 

 tures or suspensions containing it. Babbits are 

 especially susceptible, usually dying in less than 

 thirty-six hours of an acute bacteremia. Like cul- 

 tures or suspensions injected subcutaneously into 

 cholera immune pigs produce as a rule a transient 

 local reaction. Small doses injected intravenously 

 may or may not prove fatal, but large intrave- 



