THE INFECTIOUS DISEASES 229 



The enlargement and infiltration may spread from tlie patches to 

 the surrounding mucous membrane, so that the patches appear very 

 large ; a number of them may become fused together, and there may even 

 be an annular infiltration entirely around the lower end of the ileuin. 

 The infiltration, limited at first to Peyer's patches, may extend outward 

 into the muscular coat, and appear in the peritoneal coat as small, gray, 

 rounded nodules. This condition is usually found only with a few 

 patches in the lower end of the ileuin; sometimes in the caecum and 

 appendix vermiformis. 



The solitary nodules are affected in the same way as Peyer's patches. 

 They may be hardly enlarged at all, or be quite prominent, or may be 

 affected over a larger portion of the intestine than are the patches. 

 Very rarely the solitary nodules are enlarged, while the patches are not 

 at all or but slightly affected. 



The inflammation and enlargement of the agminated and solitary 

 nodules may be followed by a healing process. The character of this 

 process varies according to the intensity of the previous inflammation. 



If the reaction be slight and the enlargement of the nodules moderate, 

 the enlargement gradually disappears, and they resume their normal 

 appearance (resolution). In moderate enlargements of Peyer's patches 

 resolution proceeds first in the nodules, leaving the septa between Them 

 for a time still swollen and prominent. This gives to the surface of a 

 patch a reticulated appearance. After a time, however, the entire patch 

 becomes flattened and uniform. On the other hand, the solitary nodules 

 or the separate nodules of a patch may soften, break down, and their 

 contents are discharged with some attendant haemorrhage. This leaves 

 a bluish-gray pigmentation, due to altered haemoglobin, in the situation 

 of each nodule, and this may remain for years. 



In more severe tvpes^of the disease the enlargement of the nodules and 

 Peyer's patches ends in ulceration. This takes place in two ways: 



(a^" The enlarged nodules or patches become necrotic, soften, break 

 down, and discharge, into the intestine. t In this way are formed small 



ulcers (Fig. 110). These ulcers in- 

 crease in size by the same softening 

 process, which gradually extends at 

 their edges, and in this way ulcers of 

 large size may be formed. 1 The 

 ulcers may extend outward to the 

 muscularis or to the peritoneal coat, 

 or they may involve* the peritoneal 



FIG. UO.~HYPERPI.ASIA OF PETER'S PATCH IN coat also aud perforate. 



TYPHOID FKVER WITH SMALL ULCERS. (&) In the Severest forms of the 



The separate small ulcers are extending and disease Considerable portions' of the 

 have in part coalesced. 7 ^ ^. -^ ^ 



enlarged patches may slough and 

 become detached, leaving large ulcers^ with thick,^ overhanging edges 



1 Owing to the frequent involvement of Peyer's patches, the larger intestinal ulcers 

 in typhoid fever are apt to have their longest diameter lengthwise of the gut in con- 

 trast to spreading tuberculous ulcers, which, owing to the extension of the local inflam- 

 mation along the encircling lymph channels, are apt to have the longest diameter 

 crossing the gut. But exceptions to this general rule are common. 



