156 "^he Philippine Journal of Science 1917 



rounding mucosa, giving the ulcer an inverted bowl shape and 

 leaving considerable submucosa in apposition to the undermined 

 mucosa. Surrounding the ulcers the submucosa is oedematous, 

 thickened, and more or less infiltrated with round cells and 

 polymorphonuclear neutrophiles in groups and more scattered. 

 The infiltration is closely limited to the ulcer and is least in 

 evidence beneath the intact mucosa beyond the margins. The 

 margins of the ulcer are densely infiltrated and show consider- 

 able necrosis. Here the blood vessels are widely dilated, some 

 being ruptured and many partially or completely obliterated 

 with fibrin thrombi. 



The openings of the ulcers through the mucosa vary from 

 wide openings of 1 to 2 centimeters to fistulous openings of 1 

 to 2 millimeters in diameter, and these communicate with large 

 cavities in the submucosa which are filled with balantidia and 

 necrotic material. Some of the superficial ulcers involve the 

 solitary lymphoid follicles. Balantidia are found scattered 

 through these follicles, and also there may be groups of twenty 

 or more balantidia found in the lateral deep margins of the 

 ulcers. 



The balantidia invading the deeper part of the submucosa 

 are found at the lateral extremities of the ulcers in groups of 

 fifty to a hundred, where there is usually much necrotic material 

 about them and much peripheral cellular infiltration. Scattered 

 through the base and intermingled with the necrotic contents 

 of the ulcer, they are in small numbers and usually singly. 

 They are also present in the tissues about the ulcers, singly 

 and in groups, where they are surrounded by a dense cellular 

 infiltration. They may be seen within the blood vessels of the 

 margins and bases and elsewhere in the submucosa in close 

 relation to the ulcers. The balantidia occur in large and small 

 groups where the submucosa is intact about them, although in 

 this case they are in close relation to an ulcer or the mucosa 

 over them shows- inflammatory changes. Here there may be 

 much or little cellular infiltration about them. Those found 

 in vessels or singly are not surrounded by any cellular infiltra- 

 tion, while those in groups are surrounded by more or less cellu- 

 lar infiltration. 



Changes in the muscle.— The muscle is involved by, and forms 

 the base for, the most extensive ulcers, at which places it is 

 infiltrated with plasma cells, round cells, and polymorphonuclear 

 neutrophiles in groups and scattered and shows some necrosis. 

 The blood vessels about the involved areas are widely dilated 

 and surrounded by cellular infiltration. The subserous tissue 



