202 ESSENTIALS OF BACTERIOLOGY 



Form. One of the smallest forms of bacilli known; very thin, 

 seldom longer than i //, looking at first like little needle-like 

 crystals. Spores have not been found. 



Properties. They are motile; do not liquefy gelatin. 



Growth at ordinary temperature, very slowly, and the less 

 oxygen, the better the growth. 



Gelatin Plate. On third day little silver-gray specks, seen 

 best with a dark background, coalescing after a while, pro- 

 ducing a clouding of the entire plate. 



Stab-cultures. In a few days a very light, silvery-like cloud- 

 ing, which gradually involves the entire gelatin; held up 

 against a dark object, it comes plainly into view. 



Staining. All ordinary dyes and Gram's method also. 



Tissue sections stained by Gram's method show the bacilli in 

 the cells, capillaries, and arterioles in great numbers. 



Pathogenesis. Swine, mice, rabbits, and pigeons are sus- 

 ceptible; guinea-pigs and chickens, immune. 



When swine are infected through food or by injection, a tor- 

 pidity develops with diarrhea and fever, and on the belly and 

 breast red spots occur which coalesce, but do not give rise to 

 any pain or swelling. The animal dies from exhaustion in 

 twenty-four to forty-eight hours. In mice the lids are glued 

 together with pus. 



At the autopsy the liver, spleen, and glands are enlarged and 

 congested, little hemorrhages occurring in the intestinal mucous 

 membrane and that of the stomach. 



Bacilli are found in the blood and in all the viscera. 



One attack, if withstood, protects against succeeding ones. 



Immunity. Has also been attained by injecting vaccines of 

 two separate strengths. 



Bacillus Murisepticus (Koch) ; Mouse Septicemia. 

 Origin. Found in the body of a mouse which had died from 

 injection of putrid blood, and described by Koch in 1878. 



Form. Differs in no particular from the bacillus of swine 

 erysipelas, excepting that it is a very little shorter, making it 

 the smallest known bacillus. Spores have been found, the cul- 

 tures exactly similar to those of swine erysipelas. 



