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undermining being either incipient or obscured by the process of 

 healing. However, and tliis is not uncommon, a truly pathog- 

 nomonic picture is presented wlien the mucous membrane shows 

 all the types of lesions, and in which the walls of the gut are 

 thickened and cedematous. 



The various lesions many not be sharply distinguished, for the 

 process is a progressive one, and one type shades into another very 

 gradually, so that only for purposes of convenience in description 

 we shall arbitrarily designate the various stages of the gross process. 



I. Preulceration. — This stage is characterized by the presence of 

 the "small raised dots" of Eogers, which vary in size from 0.5 to 3 

 millimeters in diameter and are intensely congested. As a matter 

 of fact, when studied macroscopically, they are seen to be composed 

 of one or more capillary hemorrhages into the intraglandular tissue. 

 Usually associated with this condition is one of erosion of the super- 

 ficial layers of the mucous membrane. However, these erosions may 

 be encountered in the absence of any marked congestion, although a 

 moderate injection, at least, is the rule. With both of these proc- 

 esses there is little of the marked thickening of the submucosa which 

 is so constantly seen in the more active ulcerative stages of the 

 disease. These early lesions may be seen in any portion of the 

 affected gut. By using the sigmoidoscope we have demonstrated 

 them low down in the rectum within a couple of inches of the anus. 

 Tliey are most frequently encountered and are most numerous in 

 the more acute cases, but may also be seen in chronic ones. 



II. Ulceration; (a) type of Harris. — These lesions, though 

 rarer than the classic type, are nevertheless not imcommon. They 

 are possibly the result of the process of erosion mentioned above 

 and are primarily confined entirely to the mucous membrane. As 

 Harris says, they "generally reach into the submucosa and rarely to 

 the circular muscle, but never deeper." They probably commence 

 as a very circumscribed erosion and spread laterally as rapidly as 

 they do downwards. Macroscopically the edges are abrupt, some- 

 times giving the ulcer a "punched-out" appearance. They are 

 round or oval in form and their edges are usually thickened and 

 marked by intense congestion. Their bases are comparatively clean, 

 grayish, and cedematous. They are often situated on the apices of 

 intestinal folds and have a tendency to increase in the direction of 

 the short axis of the bowel. This type of ulcer has a general dis- 

 tribution and may be encountered in any part of the bowel. It is 



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