We have seen how pigment artificially introduced into the lymphatics is arrested at the glands. Similarly, carbonaceous pigment is carried from the lungs and deposited in the bronchial glands. Again, in cases of extravasation of blood, or in inflammations with considerable haemorrhage, the red corpuscles are conveyed, sometimes in large numbers, to the glands, which may thus be deeply coloured. The dissolved colouring matter in haemorrhages may also be conveyed and stain the glands.

The pigment is carried, in part at least, by the lymphoid cells, which are to be found in the lymphatic fluid. Arrived at the gland, the pigment is first caught by the stellate cells which form the reticulum in the sinuses of the cortex, and hence in the earlier stages we may have the sinuses marked out by the pigmentation. If it continues to arrive at the gland, it extends into the follicles and finally the whole gland may be deeply and uniformly coloured. When present in such quantity the pigment, although generally non-irritating, produces a Chronic inflammation. There is increase of the connective tissue forming the trabecular, and a corresponding atrophy of the glandular follicles. The affected gland in addition to the pigmentation is enlarged and hard, or indurated, and in this state it is probably to a large extent stuffed up by the pigment and rendered impervious. When this is the case the lymph probably passes by anastomosing vessels to other glands, which in their turn become pigmented. In this way we may explain how pigmentation sometimes extends from gland to gland. Thus in anthracosis of the lungs we may have not only the bronchial glands but also those of the mediastinum, and even those of the abdomen and at the porta of the liver pigmented.

What has been said in regard to pigment applies also to other solid materials introduced similarly into the lymphatics. In stone-masons the particles of stone which get into the parenchyma of the lung are in part carried to the glands, where they produce similar changes to those mentioned, but even more readily, as from their mechanically irritating characters'they are more apt to produce chronic inflammation.