In addition to its tendency to infiltrate adjacent tissues and organs, cancer is also liable to give rise to _secondary growths_. These are most often met with in the nearest lymph glands; those in the neck, for example, becoming infected from cancer of the lip, tongue, or throat; those in the axilla, from cancer of the breast; those along the curvatures of the stomach, from cancer of the pylorus; and those in the groin, from cancer of the external genitals. In lymph vessels the cancer cells may merely accumulate so as to fill the lumen and form indurated cords, or they may proliferate and give rise to secondary nodules along the course of the vessels. When the lymphatic network in the skin is diffusely infected, the appearance is either that of a multitude of secondary nodules or of a diffuse thickening, so that the skin comes to resemble coarse leather. On the wall of the chest this condition is known as _cancer en cuirasse_. Although the cancer cells constantly attack the walls of the adjacent veins and spread into their interior at a comparatively early period, secondary growths due to dissemination by the blood-stream rarely show themselves clinically until late in the course of the disease. It is probable that many of the cancer cells which are carried away in the blood or lymph stream undergo necrosis and fail to give rise to secondary growths. Secondary growths present a faithful reproduction of the structure of the primary tumour. Apart from the lymph glands, the chief seats of secondary growths are the liver, lungs, serous membranes, and bone marrow.