The Roentgen-ray picture of the normal or abnormal thorax invariably shows certain opacities corresponding to the hilus of the lung. Latent tuberculosis is found in this same location, and it has been stated that tuberculosis always begins here and spreads through the lung in a peripheral direction. It is of prime importance, therefore, to ascertain if possible the cause of these opacities.
An attempt was made to analyze the roentgenogram of the thorax by taking a cadaver and making a Roentgen-ray plate of the thorax intact; of the thorax with heart and lungs removed; of the posterior thoracic wall alone ; of the detached heart and lungs ; of the heart separate ; of the lungs freed from the heart and vessels, and finally of the lungs with the bronchi, artery, or vein injected with opaque emulsion of barium sulphate, or with citrated blood.
The cadaver was that of a negress,