From the frequency with which the osseous plates of the aorta are associated with the fatty and fibrous changes in chronic inflammation of the intima, the so-called atheromatous degeneration of the same, it is customary to speak of the calcified artery at the wrist or temple as an atheromatous artery or as evincing an atheromatous degeneration. The common feature in the aortic changes and in the calcified muscular coat is the element of age. They are frequently, though not necessarily, associated. The one is the result of an inflammatory process productive of a new, fibrous, tissue in which the calcium salts are infiltrated; while the other is due to a deposition of the latter in the normal, pre-existing, muscular elements of the vessel. Calcification and ossification of blood-vessels are frequent when the latter become dilated, as in aneurisms, whether these occur as circumscribed tumors or as a serpentine elongation and widening of the affected vessel. Cartilage is also a tissue which presents a double relation to calcareous deposition. On the one hand, there may exist an ossification resulting from the extension of a growth of bone from the perichondrium into the cartilage. The structure of this bone presents all the details found in {89} normal bone--lacunæ, lamellæ, and marrow-spaces. On the other hand, a section of the cartilage, especially the costal cartilages, may contain opaque, gray, or grayish-yellow patches, grating under the knife, which are wholly due to the presence of calcium salts in the hyaline intercellular substance of the cartilage. This calcification of the cartilage, which may also involve the capsules of the cells, is frequently associated with an ossification, although this relation is in no way essential. Calcification of the placenta, of the fibrous framework of the lungs, of the mucous membrane of the stomach, or of the atrophied glomeruli of the kidney, are well-recognized instances of the infiltration of calcareous material in normal or atrophied tissues. On the contrary, ossification of the fibrous inflammatory products of the pleura, pericardium, and peritoneum are instances of a pathological bone-formation, analogous in its nature to that met with in the intima of the aorta. The fibrinous and fibrino-cellular products of the inflammation of serous surfaces are favorable positions for the deposition of calcium salts, as are thrombi arising from the walls of blood-vessels. The latter are rather instances of the calcification of dead parts, analogous to the members of the group which includes the formation of calculi and concretions, the calcification of the dead foetus in abdominal parturition, of cheesy lymphatic glands, and of cheesy material in the lungs and elsewhere. Finally, there remains the calcification of tumors of the most varied nature, the salts being present either in living or dead parts of the tumor.