392 DISEASES OF THE G ASTRO-INTESTINAL TRACT. 



In adults, though the small intestine and colon may rarely be 

 involved, the rectum is the part of the intestinal tract most 

 frequently affected. 



TUMORS. 



Carcinoma is the most important and most frequent tumor 

 affecting the intestinal tract, though not nearly as common as 



FIG. 183. 



Alv 



Section showing degenerative changes in carcinoma of the rectum : Me, mucosa ; 

 Smc, submucosa ; M. int, inner muscular fibres (circular) ; M. ext, outer muscular 

 fibres (longitudinal); V, bloodvessels ; Ad, margin of growth, showing hyper- 

 trophied follicles and submucous tissue infiltrated with new adenoid tissue ; 

 X, mucus; Ca, ulcerated portion of the superficial surface of the growth ; XX, 

 remains of gland-follicles still recognizable ; Alv, glandular recesses dilated into 

 distinct alveoli; Col, large alveoli filled with mucoid or colloid material; Str. 

 stroma; Met, adenoid proliferation infiltrating deeper layers of bowel-wall 

 (Esmarch). 



in the stomach. In the small intestine it is rare, the duode- 

 num near the opening of the bile-duct being the point at 

 which it usually is situated. More frequently it occurs in the 



