BUREAU OF ANIMAL INDUSTRY. 517 
Although the lesions seemed to us at first sight different from the 
ulcerations found in hog cholera, yet it was only after the futile 
search for the specific bacterium of this disease in the spleen of the 
affected animals that we ventured to consider them as something 
entirely different from the lesions produced by that disease. 
In the following pages we shall try to state as clearly as possible 
the difference between the appearance presented by the large intes- 
tine in hog cholera and in swine plague. 
Croupous and diphtheritic lesions.—The mucous membrane is 
dotted by a large number of closely set, convex, circular masses of 
a yellowish tint. These are rarely larger than one-eighth to one- 
fourth inch in diameter. They can be readily lifted away from the 
membrane, leaving aslightiy depressed, raw surface. Thismass which 
has exuded from the membrane is tough, evidently made up of a 
fibrinous coagulum. It is very easily mistaken for an ulcer when 
the examination is carelessly made. The hog-cholera ulcer, it will 
be remembered, is a circumscribed death or necrosis of the mucous 
membrane. The hole thus made is occupied by a soft, granular 
matter, in some cases projecting above the surface like a button, 
which is scraped away with some difficulty, leaving an irregular ex- 
cavation. Very rarely the ulcers are flat, button-like masses, pre- 
senting concentric bands of a dirty yellow and black. They are 
then made up of hard, tough, homogeneous, whitish tissue, extend- 
ing at times as a neoplasm through the entire intestinal wall to the 
peritoneum. These ulcers vary much in size, from a pins’ head to 
an inch or more in diameter. The lesions found in swine plague are 
therefore different in that they consist of masses of exudate, either 
isolated or running together into large patches of variable size and 
thickness. The rectum (rarely diseased in hog cholera) is quite fre- 
quently involved with the colon. In some cases a continuous sheet 
of deposit covers the mucosa entirely. This may adhere with con- 
siderable tenacity, or it may be removed simply by the stroke of the 
scalpel, or it may not be attached, but appear as a part of the intes- 
tinal contents. It then consists of small lumps stained with bile and 
feces and easily overlooked. Sections of the intestinal wall show 
the exudate to consist of mesh-work which may or may not inclose 
leucocytes. When the inflammation is very severe the membrane 
beneath the exudate is hable to necrosis, and the process must then 
be regarded as diphtheritic. It is probabale that in all cases the epi- 
thelium is destroyed in order to give rise to the exudate, and all va- 
rieties of lesions, from the simply croupous to the diphtheritic, are to 
be met with, depending on the quantity and quality (or virulence) 
of the infectiousagent. The anatomical distinction between croupous 
and diphtheritic lesions seem at least in this disease to be simply 
due to amore or less intense action of the same cause. In diph- 
theritic conditions therefore, ulcers may subsequently appear. Our 
observations on this stage of the process are too few to warrant any 
conclusions. Once or twice ulcers were seen which differed from 
hog cholera ulcers in being perfectly round, as if punched out of the 
membrane, from one-eighth to three-eighths of an inch in diameter. 
The bottom of the ulcers was concealed by a thin, creamy deposit, 
the border slightly thickened and very red. There was no adherent 
slough. Some of the ulcers corresponded with the mouths of the 
flask-shaped mucous glands. 
The exciting cause seems to attack the membrane from the sur- 
face, for the submucous tissue is not infiltrated with cells to any 
