388 BIOLOGY OF THE LABORATORY MOUSE 



The simplest method for tentative diagnosis is to culture the heart's 

 blood, spleen, liver, or intestinal contents on one of the selective media 

 which differentiate the non-lactose-fermenting from the lactose-fermenting 

 colonies (Endo or eosin-methylene blue agar plates) or which inhibit the 

 coliform organisms (McConkey, bismuth sulphite, or desoxycholate agar 

 plates). Single colonies of gram-negative bacilli may then be hshed to 

 Russell's double sugar slants and subsequently to lead acetate medium. 

 The production of acid and gas in the stab or butt portion of the former 

 and of black lead sulphide in the latter tentatively identifies the organism 

 as one of the Salmonella group. Further identification may be accomplished 

 by the biochemical reactions (as outlined above) and the determination of 

 the antigenic structure either by cross-absorption tests with known aggluti- 

 nating antisera or by agglutinations with antisera previously absorbed to 

 remove all but specific antibodies. 



Infections with related organisms. — Four unusual epidemics in mice due 

 to Salmonella or related organisms have been reported. Sangiorgi (233) 

 noted a spontaneous disease which involved approximately 20 per cent of 

 his white mice and was apparently due to a coliform bacillus. The affected 

 animals showed ruftled hair, shallow respirations, subnormal temperature, 

 weakness or paralysis of the hind extremities, marked emaciation, and 

 profuse diarrhea with staining of the perianal region. The pathological 

 findings were not unlike those described above: grayish-white necrotic 

 lesions in the liver, hypertrophied and congested spleen, pale kidneys, 

 intestines filled with yellowish, foamy, liquid contents, and serous exudate 

 in the abdominal cavity. The organisms cultured from the heart's blood 

 and spleen were short, gram-negative rods which produced acid and gas in 

 glucose, maltose, lactose, and saccharose and formed indol. Inulin and 

 starch were not fermented. Colonies on Drigalski medium showed the 

 typical red color of colon bacilli. These characteristics placed the organism 

 in the colon group. White mice fed cultures of the bacillus died in 5 to 6 

 days with a profuse diarrhea. The pathological findings were identical 

 with those of the spontaneous disease. 



Spontaneous infections with Morgan's bacillus have occurred in labora- 

 tory mice fed on a diet of oats and raw beef (337). The mice displayed an 

 appearance of " unthriftiness and lethargy" which was unlike that of mice 

 in other epidemics. The chief signs were a rough and shaggy coat, hunched 

 up posture, retracted abdomen, anorexia, and occasionally antemortem 

 convulsions. At autopsy, there was a general pallor and dryness of the 

 tissues, the heart was dilated and flabby, the liver nutmeg, and the kidneys 



