The calcification and ossification of the cardiac valves and the calcification of attached thrombi, furnish frequent and constant occasion for disturbances in the functions of the heart, resulting in dilatation and hypertrophy, with the sequence of symptoms of chronic valvular endocarditis. The great clinical importance of the presence of calcium salts in the circulatory apparatus is such that further reference in this place to its results is unnecessary, as its special relations are more important than its general features. Calculi act as local causes of inflammation, and their presence is likely to be followed by ulceration, abscess, and stenosis, perhaps obliteration, of the smaller canals in which they may lie. _Pigmentation._ The pathological pigmentation of the body results, presumably, from the metamorphosis of the coloring matter of the blood or from the introduction from without of pigments insoluble in the fluids of the body. The former of these methods has recently been studied by Langhans[39] and Cordua,[40] and the present views of this subject are chiefly due to their observations, as well as to the earlier investigations of Virchow and others. [Footnote 39: _Virchow's Archiv_, 1870, xlix. 66.] [Footnote 40: _Ueber Resorptionsmechanismus von Blutergüssen_, Berlin, 1877.] The hæmoglobin contained in red blood-corpuscles is considered to be composed of a coloring matter, hæmatin, combined with an albuminate, globulin. When blood is removed from the body the hæmoglobin is readily separated from the corpuscles by various agents, and is then dissolved in the plasma, which becomes lac-colored. This solubility of the hæmoglobin is of importance in connection with the absorption of extravasated blood. During the time necessary for this process to take place, observable changes are apparent in the color of the affected part when its seat is superficial, especially cutaneous. These changes in color are largely dependent upon the modifications undergone by the hæmoglobin.