80 REPORT OF THE BUREAU OF ANIMAL INDUSTRY. 



predominate. In some of the animals in this outbreak there were 

 most extensive hemorrhages. In one the mucous membrane of the 

 stomach was separated from the muscular coat by an extensive clot 

 one-half inch thick. In five cases (10 per cent.) the lungs were the 

 seat of extensive hemorrhages, which literally converted the most de- 

 pendent lobes into a blood clot and filled the pleural sacs with blood- 

 stained serum. In a variable number both peritoneal and thoracic 

 cavities contained much blood-stained serum. 



Ulcerative lesions. Ulcers of the large intestine were present in 

 36 out of 49 cases, or 70 per cent. They varied from very slight to 

 very severe and extensive lesions, involving in a small number 

 nearly the whole mucous membrane of the caecum and colon. The 

 rectum was quite invariably free from disease. The age of the ulcers 

 can not be determined, as the process of necrosis and subsequent 

 ulceration seems to vary very much in rapidity. In a few cases it 

 was not limited to the mucous membrane, but extended into the mus- 

 cular wall, producing considerable local inflammation and thickening 

 of the serous membrane. In rare cases the necrosis and cellular in- 

 filtration had made the intestinal wall so friable that it broke when 

 handled. When the ulceration was slight, it was frequently con- 

 fined to the ileo-csecal valve and adjacent membrane, where the mu- 

 cpsa is pitted with small mucous glands. The ulceration in this 

 situation was accompanied by an extensive neoplastic thickening of 

 the valve beneath the ulcer, indicating that the ulcer was old. In 

 5 cases (10 per cent.) the lower ileum was ulcerated; the ulcers 

 seemed to have no relation to Peyer's patches. 



Very puzzling to the pathologist is the frequent combination of 

 old ulceration with recent hemorrhagic lesions (about 20 per cent.). 

 Is it due to an increase in the virulence of the bacteria in the re- 

 cesses of the ulcer, so that when carried into the circulation they are 

 able to live in the capillaries, there to multiply until the colonies 

 cause necrosis of the vascular wall, or is it due simply to the intro- 

 duction of bacteria into the circulation from the ulcerated region 

 without any increase in virulence ? These questions are of great 

 practical importance in the final solution of the problem how 

 severe epidemics may suddenly arise, and seemingly from mild, 

 chronic cases. 



Complications. Peritonitis, pleuritis, and pericarditis were not 

 uncommon complications, usually accompanying old ulceration. 

 These may be caused by septic bacteria gaining entrance through 

 the ulcerations. In fact, cocci, closely resembling those of suppura- 

 tion, are usually found in the peritoneal cavity of chronic cases. 



Lung lesions. This epizootic was studied mainly for the purpose 

 of determining the condition of the lungs in hog cholera. The 

 lesions found on post mortem examination were either simple col- 

 lapse or lobular broncho-pneumonia following it. 



Simple collapse usually involved the two ventral dependent lobes,* 

 more rarely portions of the small cephalic and the principal lobes. 

 The collapsed lobes, or groups of lobules interspersed among em- 

 physematous lobules, appeared slightly if at all depressed. The color 

 approached that of muscular tissue. In only a few instances could 

 plugs be found occluding the bronchus. 



Sections made from lobules in this condition show a number of 

 interesting features. The alveolar walls are crowded together in 

 some places till they almost touch one another. 



* See p. 65 for nomenclature of lobes of pig's lung. 



