=Gums.=--Where it has been possible to examine the gums of early cases, where swelling, redness or bluish discoloration are the chief symptoms and before secondary infection has set in, the microscopic picture is very similar to that of the skin. Small hemorrhages, round-celled infiltration, increase of connective tissue, clumps of pigment containing cells, or a diffuse deposit of brownish granules complete the picture. Congestion and edema are usually evident. The changes are most pronounced in the deeper layers of the submucosa and about the muscles, leaving the superficial layers strikingly intact, beneath an apparently normal epithelium. In the later stages, erosion of the mucosa occurs, and the upper layers of submucosa become involved. Polynuclear cells appear in great numbers, abscesses and ulcers are formed, which with proper staining can be shown to harbor the various types of mouth bacteria, cocci, spirillæ, etc. The pigmentation becomes intense, and a marked increase of the newly-formed connective tissue takes place. The lesions of the stomach are neither characteristic nor, as a rule, very striking. Hemorrhages occur, the larger ones generally in the subperitoneal layers, the smaller ones in any of the coats. Thickening of the wall follows or accompanies these hemorrhages. Superficial erosions of the mucosa or even ulcers may be seen. The striking congestion of the duodenum has been fully discussed in considering the gross pathology. At any level in the intestinal tract hemorrhage may take place, with the resulting pigmentation and scar tissue formation. The lymphoid structures--solitary follicles and Peyer's patches--are usually intensely congested and often the seat of hemorrhage. They constitute the sites of predilection for ulcerative processes of the gut. Bacteria can be demonstrated at times in the submucous layers; however, no type has been found to predominate, the flora being composed of the usual intestinal forms. Aschoff and Koch have demonstrated in these ulcers the spirilla and fusiform bacilli so commonly found in the mouth. These follicular ulcers may be found in any part of the intestine, and may be shallow erosions, or extend through the follicle into the deeper tissues. Hemorrhages are commonly located about the follicles. The epithelial layer is edematous, often showing an increased number of cells. The lymph-nodes may be congested, or edematous and hemorrhagic. Pigment is usually present and in some cases the peripheral sinus is distended with pigment-loaded cells. Where secondary infection has occurred, extensive necrosis of the glands is seen. This is found frequently in mesenteric nodes where severe intestinal lesions are present. The nodes lying in the drainage paths of hemorrhagic areas, especially the inguinal nodes, show active resorption of blood and blood pigments, and, as noted above, may be the seat of infection.