The small ulcers which, as we have seen from the above statistics, are present in a certain proportion of cases in the mucous membrane of the colon, and more rarely in that of the small intestine when the inflammation has been protracted and of a severe type, appear to occur in the solitary glands and in the mucous membrane surrounding them. While some of these glands in a specimen are simply tumefied, others are slightly ulcerated, and others still nearly or quite destroyed. The ulcers are usually from one to three lines in diameter, circular or oval, with edges slightly raised from infiltration. Rarely, I have seen minute coagula of blood in one or more ulcers, and I have also observed ulcers which have evidently been larger and have partially healed. The ulcers are more frequently found in the descending colon than in other portions of the intestines. When ulcers are present they commonly occur in the descending colon, or if occurring elsewhere they are most abundant in this situation.

According to my observations, these ulcers are found chiefly in infants over the age of six months—during the time, therefore, when there is greatest functional activity and most rapid development of the solitary glands. Peyer's patches, though frequently prominent and distinct, have not been ulcerated in any of the cases observed by me.

The appendix vermiformis participates in the catarrh when it occurs in the caput coli, its mucous membrane being hyperæmic and thickened. In certain rare cases the inflammation is so intense that a thin film of fibrin is exuded in places upon the surface of the colon. It is apt to be overlooked or to be washed away in the examination. The rectum usually presents no inflammatory lesions, or but slight lesions in comparison with those in the colon. It usually remains of the normal pale color, or but slightly vascular even when there is almost general colitis. Hence the infrequency of tenesmus.

As might be expected from the nature of the disease, the secretion of mucus from the intestinal surface is augmented. It is often seen forming a layer upon the intestinal surface, and it appears in the stools mixed with epithelial cells and sometimes with blood and pus.

The mesenteric glands in cases which have run the most protracted course and end fatally are found more or less enlarged from hyperplasia. They are frequently as large as a pea or larger, and of a light color, the color being due not only to the hyperplasia, but in part to the anæmia. Occasionally, when patients have been much reduced from the long continuance of the diarrhoea, and are in a state of marked cachexia at death, we find certain of these glands caseous.

The condition of the stomach is interesting, since indigestion and vomiting are so commonly present. I have records of its appearance in 59 cases, in 42 of which it seemed normal, having the usual pale color and exhibiting only such changes as occur in the cadaver. In the remaining 17 cases the stomach was more or less hyperæmic, and in 3 of them points of ulceration were observed in the mucous membrane.

All physicians familiar with this disease have remarked the frequency of stomatitis. In protracted and grave cases it is a common complication. The buccal surface in these cases is more vascular than natural, and if the vital powers are much reduced superficial ulcerations are not infrequent, oftener upon the gums than elsewhere. The gums are apt to be spongy, more or less swollen, bleeding readily when rubbed or pressed upon. Thrush is a common complication of the summer complaint in infants under the age of three or four months, but is infrequent in older infants. Occurring in those over the age of six or eight months, it has an unfavorable prognostic significance, indicating a form of summer diarrhoea which commonly eventuates in death.

The belief has long been prevalent in the past that the liver is also in fault. The green color of the stools was supposed to be due to vitiated bile. But usually in the post-mortem examinations which I have made I have found that the green coloration of the fecal matter did not appear at the point where the bile enters the intestines, but at some point below the ductus communis choledochus in the jejunum or ileum. The green tinge, at first slight, becomes more and more distinct on tracing it downward in the intestine. It appears to be due to admixture of the intestinal secretions with the fecal matter.

I have notes of the appearance and state of the liver in 32 fatal cases. Nothing could be seen in these examinations which indicated any anatomical change in this organ that could be attributed to the diarrhoeal malady. The size and weight of the liver varied considerably in infants of the same age, but probably there was no greater difference than usually obtains among glandular organs in a state of health. The following was the weight of this organ in 20 cases:

Age.Weight. Age.Weight.
4 weeks5 ounces. 10 months6¾ ounces.
2 months3½ ounces. 13 months6 ounces.
2 months3½ ounces. 14 months9 ounces.
4 months5 ounces. 15 months6 ounces.
5 months6½ ounces. 15 months7½ ounces.
5 months9 ounces. 15 months9½ ounces.
7 months4½ ounces. 16 months6 ounces.
7 months6 ounces. 19 months4½ ounces.
7 months6¼ ounces. 20 months9¼ ounces.
9 months8 ounces. 23 months15 ounces.