INFECTIOUS DISEASES OE CATTLE. 453 



nasal septum, and pulmonary and intestinal necrosis, accompanying 

 hog cholera. Abscesses of the liver, gangrenous processes of the lips 

 and nose, and gangrenous affections of the hoof have all been caused 

 in sheep by this organism. 



Pathology. — The principal lesions in necrotic stomatitis occur in the 

 mucous membrane of the mouth and pharynx. The alterations may 

 extend to the nasal cavities, the larynx, the trachea, the lung, the 

 esophagus, the intestines, and to the hoof. The oral surfaces affected 

 are, in the order of frequency, tongue, cheeks, hard palate, gums, 

 lips, and pharynx. In the majority of cases the primary infection 

 seems to occur in the tongue. (PI. XLV.) 



Infection takes place by inoculation. Some abrasion or break in 

 the continuity of the mucous membrane of the mouth occurs. Very 

 likely the origin may be connected with the eruption of the first teeth 

 after birth, or, in animals somewhat older, the entrance of a sharp- 

 pointed particle of food. Gaining an entrance at this point, the bacilli 

 begin to multiply. During their development they elaborate a toxin, 

 or poisonous substance, which causes the death, or necrosis, of the epi- 

 thelial, or superficial, layer of the mucous membrane and also of the 

 white blood cells which have sallied forth through the vessel walls to 

 the defense of the tissues against the bacillary attack. This destruc- 

 tion of the surface epithelium seems to be the essential factor in the 

 production of the caseous patch, often called the false membrane. 

 From the connective tissue framework below is poured forth an inflam- 

 matory exudate highly albuminous or rich in fibrin-forming elements. 

 When this exudate and the necrosed cellular elements come in con- 

 tact, the latter furnish a fibrin ferment which transforms the exudate 

 into a fibrinous mass. This process is known as coagulation necrosis, 

 and the resulting fibroid mass, containing in its meshes the necrosed 

 and degenerated epithelium and leucocytes, constitutes the diphtheric 

 or false membrane. Did the process cease at this point it would be 

 properly called a diphtheric inflammation. But it does not. A case- 

 afcing ferment is supplied by the bacilli, and this, acting upon the 

 fibroid patch, transforms it into a dry, finely granular, yellowish mass 

 of tissue detritus resembling cheese. 



Frequently this caseous inflammation results in the formation of 

 one or more ulcers with thickened, slightly reddened borders, sur- 

 mounted by several layers of this necrosed tissue. The floor of the 

 ulcer is formed by a grayish yellow, corroded surface, under which 

 the tissue is transformed into a dry friable or firm cheesy mass. 

 In the tongue this may progress to two fingers' thickness into the 

 muscular portion; in the cheek it may form an external opening, 

 permitting fluids to escape from the mouth; upon the palate it fre- 

 quently reaches and includes the bone in its destructive course; upon 

 the gums it has produced necrosis of the tooth sockets, causing loss 

 of the teeth. In the advanced forms, caseous foci may be seen in the 



