INFECTIOUS DISEASES OF MICE 397 



deal of polymorphism in older cultures. It stains irregularly with the 

 aniline dyes, and is gram-positive and non-motile. Growth occurs aerobi- 

 cally on ordinary media and on Loeffler's serum medium at 37°C. Acid is 

 produced from dextrose, sucrose, and maltose but not from galactose, 

 lactose, mannite, and dextrin. Litmus milk is not changed; nitrates are 

 reduced; no indol is formed, and gelatin is not liquefied. Final differentia- 

 tion of this organism from other members of the group may be made on 

 the basis of its specific pathogenicity for mice. True diphtheria bacilli 

 (C. diphtheriae) have not been found in mice (95). 



Injections due to related organisms. — Condrea (46) has described an 

 extremely contagious but benign disease which spread through his mouse 

 colony, attacking 200 mice. Only a few deaths occurred from secondary 

 infection. The disease was characterized by the appearance of small, 

 movable nodules in the subcutaneous tissue of the back or thighs. These 

 foci increased in size, became adherent to the skin, and then ulcerated. 

 Yellowish, serous fluid and necrotic caseous material could be expressed 

 from the nodule after removal of the crust. Microscopically, the exudate 

 showed leukocytes and many gram-positive bacilli. The organisms were 

 easily cultured aerobically on media enriched with ascitic fluid or serum, 

 and resembled the diphtheria bacillus in morphology. The organism dif- 

 fered markedly from C. kutscheri in its fermentation reactions — acid but no 

 gas was formed in dextrose, levulose, sucrose, maltose, mannose, arabinose, 

 sorbite, dextrin, inulin, and salicin. Experimentally, the disease could be 

 reproduced by subcutaneous or intramuscular injection without generalized 

 infection. Intravenous administration produced a fatal septicemia with 

 localized abscesses in the lungs and kidneys. Rabbits were not susceptible. 

 Condrea classified the organism in the genus Corynebacterium and proposed 

 the name "Corynebacterium miiris.^' 



A somewhat similar organism was isolated by Holzhausen (loi) from 

 white mice injected with the brain emulsion of a dog suspected of being 

 rabid. Paralysis occurred on the second day, followed by death during 

 the course of the next day. The organism apparently produced a septicemia 

 without gross lesions and was readily cultured from the blood and organs. 

 Morphologically, it had the appearance of a diphtheroid which differed 

 from Condrea's organism in fermenting galactose and lactose but not 

 attacking arabinose. It produced hydrogen sulphide and, in litmus milk, 

 acid without coagulation. No exotoxin was detected. The organism has 

 been classified by Bergey (22) as Corynebacterium murisepticum. The 

 experimental disease was specific for white and grey mice. 



