348 VETERINARY BACTERIOLOGY 



and necrotic vulvitis, vaginitis, and metritis, foot-rot of cattle, 

 lip and leg ulceration of sheep, necrotic omphalophlebitis and 

 joint ill in young animals, necrosis in the alimentary tract and 

 other viscera in many animals, and possibly even avian diphtheria. 

 It is sometimes of considerable economic significance, particularly 

 in the so-called lip and leg ulceration of sheep. Some of the affec- 

 tions, particularly this latter, are known to be contagious. Much 

 work still remains to be done, however, on the different infections 

 and possible variations in virulence. 



The lesions produced in all tissues have many common charac- 

 ters. They are essentially coagulation necroses with caseation. 

 Metastatic infection is very apt to occur. The local lesion is 

 described by Mohler and Morse as a " sharply circumscribed 

 patch of yellowish or dull brown, sometimes greenish white, 

 homogeneous, structureless, dry, crumbly tissue debris of soft, 

 cheesy consistence, resembling compressed yeast, and manifesting a 

 characteristic stench. The line of demarcation between the living 

 tissue and the dead mass is a narrow hyperemic zone." A false 

 membrane is formed over the surface as a " result of coagulation 

 necrosis of the inflammatory exudate and entanglement in its 

 meshes of the hyaline degenerated tissue-cells and leukocytes." 



Immunity. It has been supposed that the organism produces a 

 true toxin because of its intense local destruction of tissue, and 

 because of the death of laboratory animals with many of the symp- 

 toms of a toxemia. The toxin has not been isolated, however. It 

 is stated that intravenous injections of the organism into the goat 

 confer an immunity. No practicable method of immunization 

 has been developed. 



Bacteriological Diagnosis. The organism may be observed in 

 mounts prepared from the tissue just surrounding the necrosed area. 

 Its appearance is characteristic enough to differentiate it from other 

 forms that may be present. Animal inoculations, preferably into 

 the rabbit, are generally necessary to secure pure cultures. 



Transmission. It is improbable that the organism ever gains 

 entrance through the unbroken skin or mucous membrane. 

 Scratches, wounds, abrasions, or injuries of other types supply an 

 infection atrium. The disease must be regarded as mildly con- 

 tagious, however. 



