Upon Serous Membranes, and the peritoneum in particular, we have, in connection with luxuriating medullary cystocarcinoma of the ovaries, met with medullary vegetations which, judging from their appearance and the arrangement of their vessels, would seem to belong to this category.

On the other hand, an examination of the preparations in the Pathological Museum of Vienna has taught us that the dentritic vegetations which often luxuriate upon synovial membranes, and in the capsule of the knee-joint so numerously that it appears invested with them as with a felt, really appertain to this class. In the interior of the hollow growths which constitute them, a development of areolar tissue takes place, just as in the cysts of the vascular plexus, of which we shall hereafter speak, until they at length become replete with it. The largish terminal bulbs of their stems and branches are frequently so flattened as to resemble linseed or melon seeds (Majo).

The entire excrescences with these numerously seated upon them, and it may be in imbricated order, acquire the aspect of foliage. In one instance we found them to contain fat-cells, which explains what Johannes Muller meant by lipoma arborescens. In fine, we doubt not that they offer the original nidus for the production of those circular, smooth, or knotted, facetted cartilage or bone-plates, which occupy the inner surfaces of synovial sacs, often attain to a considerable volume, and, by spontaneous detachment, become free bodies within the capsule.