Rindfleisch says: "The accumulation of the fluid is not produced by the continuance of the normal secretion, but by an exudation surpassing the normal measure of the serum of the blood with salts, albumen, fibrinogenous substance, and extractives, in the most varying proportions. The exudation cysts have little to do with pathological new formation. Of extravasation cysts," he says, "a parenchymatous bleeding can very well be the point of departure for the formation of a cyst. The hemorrhagic depot can present itself primarily as a cyst, namely, when the blood is poured out between two surfaces in themselves smooth; for example, bone and periosteum, cartilage and perichondrium, and thereafter remains fluid. As a cyst may also be formed when upon the one hand the limitary parenchyma furnishes a connective tissue membrane, upon the other hand, the blood itself is resorbed through a series of metamorphoses up to a small remainder, and is replaced by a clear fluid." The above-mentioned condition is liable to manifest itself within the body of the jaw, the bone and periosteum, after severe mechanical injuries to the bone, and the rupture of blood-vessels within the parenchyma. There can be little doubt that many of the so-called dentritic cysts of the jaws have their origin primarily from causes brought about by falls, strokes and mechanical violence, causing rupture of blood-vessels. It is quite true, history of cases fully confirms such facts. Clinical observations leads us to believe, however, that only in cases where the abscess does not open, we find the pathological new formation taking place within the jaws. Pulpitis, and as has been observed, followed by pericementitis and periodontitis, is a prolific cause of the development of the dentritic cystic tumor.