CHARACTERISTIC calcium densities of apparently unique morphology occur in chest roentgenograms of men having silicosis. These shadows are seen as more or less regular rings in the hilar or mediastinal regions of the chest. They have been designated as egg-shell, Eierschalen, or mulberry calcifications. They are circular or ovoid in character and consist of an irregular peripheral shell with a faint stippling throughout the enclosed tissue. Considerable divergence of opinion exists as to the cause and significance of this particular formation. There has, unfortunately, been a paucity of autopsy studies to clarify the problem. Lommel (2) was of the opinion that calcium is deposited in inflamed and dilated sinuses within the lymph node capsule and other similarly dilated lymphatic spaces. He states that similar calcifications are seen in the extreme periphery of the lung. He also mentions fine, delicate ring forms which may be early or transitional stages of the same process. Mild cases with “snow-storm” lun...