240 VETERINARY BACTERIOLOGY 



centric rings and a papillate center. In subsequent transfers 

 the colonies are confluent, dry, and cohesive. Glycerin agar 

 is not so favorable as the plain agar. Bouillon becomes turbid, 

 then clears by sedimentation, and a white, " greasy," brittle 

 pellicle forms. Gelatin is not a suitable medium, as little growth 

 occurs at room-temperatures. Blood-serum is favorable, the 

 colonies frequently becoming creamy yellow in color. Growth 

 occurs on potato and in milk. In the latter the appearance is 

 unchanged. The organism described by Preisz is recorded as 

 showing some minor differences in cultural characters from the 

 one studied by Norgaard. 



Physiology. The organism is aerobic and facultative anae- 

 robic. A little acid is formed from dextrose, .but none from 

 lactose or saccharose. No gas is developed. Neither indol nor 

 phenol is produced. The growth optimum is 37, although some 

 growth will occur at 16 to 18. The organism will resist desicca- 

 tion for several days. It is easily destroyed by disinfectants. 



Pathogenesis. Mechanism of Disease Production. The disease 

 may be characterized as a chronic caseation of the lymph-nodes, 

 without general systemic disturbances. No toxins are produced, 

 and the means by which the organism brings about its local 

 reaction is unknown. 



Experimental Evidence of Pathogenesis. Intravenous injec- 

 tion of the guinea-pig results in death in four to ten days, with 

 foci of caseation in various internal organs, particularly the lungs 

 and the liver. Subcutaneous injection is followed by enlarge- 

 ment and caseation or suppuration of the lymph-glands, result- 

 ing fatally in from fifteen to twenty-eight days. Feeding experi- 

 ments have been successful in causing infection. Similar results 

 may be reached by the use of the rabbit, the mouse, but not 

 pigeons and fowls. Experimental inoculation of sheep has repro- 

 duced the disease. 



Character of Disease and Lesions Produced. The organism has 

 been reported chiefly as a cause of ovine caseous lymphadenitis, 

 but an organism probably identical with this form has been 

 reported from similar lesions in the lungs of cattle. It is possible 

 that it likewise is identical with the type next to be described. 

 The disease of sheep is found chiefly in breeding ewes. The 



