These are rarely primary. Lipomas of small size originating from the appendices epiploicae are not uncommon. They are usually pedunculated and of small size. The tumour may become detached by narrowing of its neck and form a sessile tumour elsewhere, as on the surface of the diaphragm, in a case recently met with. Lipomata may originate from the subperitoneal adipose tissue, and may attain large dimensions. They conform to the type of Diffuse Lipomas. Nolan removed one which weighed five pounds from over the descending colon of a child 2 1/2 years old. Retroperitoneal sarcoma is not uncommon. The tumour, sometimes growing to a very large size, pushes the organs before it and may infiltrate them.

Sometimes we meet with bulky gelatinous tumours in the abdomen, and the recognition of the exact nature of some of them is matter of considerable difficulty. Colloid cancer of the stomach and intestine not infrequently, as we shall see afterwards, passes on till it reaches the peritoneum, and may result in the formation of bulky gelatinous masses there. But, besides that, there are primary tumours of the peritoneum which belong to the class of Cylindroma or Plexiform angiosarcoma. In these cases there is a new-formation of blood-vessels in whose adventitia is produced a peculiar gelatinous tissue. These tumours may attain a large size, weighing as much as forty pounds.

Primary cancer occurs with similar characters to that of the pleura, and like that form it is sometimes called endothelioma. The tumour is in the form of nodules of larger and smaller size along with great thickening of the peritoneum. There is also great serous effusion and usually also fibrinous deposition. There may be blood in the exudation.

Secondary cancer of the peritoneum will be considered in the next section.

Lympho-sarcoma is not such a common tumour here as in the mediastinum, but it sometimes originates in the lymphatic glands of the mesentery and involves all the neighbouring structures. We may thus have bulky tumours occupying the place of a portion of the mesentery and intestine, and repeating roughly the anatomical relations of these.

Literature

Physiology and General Pathology - Wegner, Langer.beck's Arch., xx.; Grawitz, Charite Annalen, 1884, p. 770; Waterhouse, Virch. Arch., cxix., 342. Malformations - Lawson Tait, Dubl. Jour, of Med. Sc, 1869; Obstet. Jour., iii. haemorrhages - Becklinghausen, Virch. Arch., xxvi., 1863; Cordua, Besorp-tionsmech. von Blutergiissen, 1877; Friedreich, Virch. Arch., lviii., 1873; Baumler, ibid., lix., 1874. Chylous ascites - Quincke, D. Arch. f. klin. Med., xxx., 1882; Coats, Museum Catalogue of Western Infirmary, (two cases from thrombosis of jugular); Letulle, Bev. d. Med., 1884; Whitla, Brit. Med. Jour., 1885, i. Inflammation - Grawitz and Waterhouse, 1. c.; Klein, Anat. of lymph, syst., i., 1873; Orth, Virch. Arch., lviii., 1873; Fraenkel, D. med. Wochenschr., 1884; Bauer, in Ziemssen's Cycl., xiv., 1878. Tuberculosis - Klebs, Virch. Arch., xliv., 1868; Payne, Path, trans., xxi., 1870; Baumgarten, Zeitschr. f. klin. Med., x., 1885; Grawitz, Charite-Annalen, xi., 1886. Lipoma - Nolan, Australasian Med. Gaz., 1898, p. 145; see also Catalogue of Path. Museum Western Infirmary, 2nd edition. Primary cancel - Bristowe, Path, trans., xxi., 1870; Neelsen, D. Arch. f. klin. Med., xxxi., 1882; Brieger, Charite-Annalen, viii., 1883. Lymphosarcoma - Wickham Legg, St. Barth. Hosp. Bep. xi., 1875.