No. 4.] KErOKT OF CATTLE BUREAU. 313 



An exhaustive description of the various lesions does not seem 

 desirable in this instance, and will not be attempted. The lesions 

 submitted for examinations may be placed, for the sake of con- 

 venience, in three groups, - — the mouth lesions, the vesicles of the 

 udders and the pustules of the udders and teats. 



Type I : Mouth Lesion. — This appeared during life as a sharply 

 circumscribed opaque area of the mucous membrane, situated on 

 the buccal pad, about 6 mm. in diameter, and slightly elevated. 

 This lesion was associated with several large, ragged ulcerations, 

 situated on various parts of the gum. 



This is found to be microscopically an area of necrotic epithelium, 

 the cells of which are dissociated by the exudation present. 

 The lesion is very superficial, involves chiefly the outer three- 

 quarters of the epithelium, and at the periphery is sharply marked 

 off from the surrounding normal epithelium. 



The epithelial cells are necrotic, and stain intensely with the 

 diffuse stain. The nuclei may be fragmented and deeply stained, 

 but in general they are very pale, and are in many instances rep- 

 resented by a light spot in the cell. The exudation is purulent or 

 fibrino-purulent in character. The underlying connective tissue 

 contains but few leucocytes. This does not correspond in any 

 essential feature to a vaccine lesion.* 



Type II: Vesicles of the Udder and Teats. — These M^ere excised 

 from cow No. 3 the second day after their appearance. One lesion 

 measures about 3 mm. in diameter, and is very superficial. An- 

 other in the same specimen has become dry, and is represented by 

 a crust. The third lesion measures 2 cm. in length, the entire 

 epithelium is destroyed, and the dermis is involved for some dis- 

 tance below. The appearances of the necrotic epithelial cells 

 agree in all respects to those of the mouth lesions. The cells are, 

 however, separated by a larger amount of fluid exudate, and either 

 the upper layers of the epidermis or the epidermis as a whole is 

 lifted up to form a vesicle. The vesicles are in all cases filled with 

 sero-fibrinous exudate, containing at this stage many leucocytes 

 and free necrotic epithelial cells. In lesions where the process is 

 more extended, the base of the vesicle is composed of tissue in- 

 filtrated with leucocytes, and there is considerable extravasation 

 of blood into the vesicle. 



Type III: Pustules and Infected Hair Follicles. — Under this 

 heading are described all those skin lesions obtained from the 

 various cows at the time of autopsy. Most of these consist of 



* Lesions identical in most respects witli that just described were found on the 

 tongues of calves which died during the vaccine experiments carried on at the 

 estate of George R. Tyzzer in the early part of August. 



