I. Sarcoma. Definition. Structure; cells, intercellular substance, blood-vessels. Place of origin. Mode of growth; local malignancy aud metastasis. Changes in structure; induration, ossification, cystic formation, ulceration, etc. Individual forms. 1. Round-celled, 2. Spindle-celled, 3. Giant-celled, 4. Pigmented, and 5. Plexiform sarcomas. Other forms described. II. Carcinoma or Cancer. Definition. Structure; cells, stroma, blood-vessels, lymphatics. Origin; from existing epithelium, shown in many cases, hence its localities where epithelium exists. Influence of age and sex. Growth and extension; frequently by infiltration; ulceration; secondary tumours in lymphatic glands; generalization by implantation of grafts; usual seats of secondary tumours; their large size; their mimicry of primary tumours. Retrograde changes; fatty degeneration, chiefly. The local nature of cancer. Individual forms. 1. Flat-celled epithelioma, including Rodent ulcer, 2. Cylinder-celled epithelioma, 3. Soft or medullary cancer, 4. Scirrhus, 5. Colloid cancer, 6. Melanotic cancer, 7. Mucous cancer, 8. Endothelioma.