Plate XXIX. Upper or dorsal surface of the lungs of the ox, reduced to one-twelfth of the natural size: a, a', the right and left principal lobes. These are the largest and are situated posteriorly, resting upon the diaphragm; b, b', the ventral lobes, situated between the principal lobes; and c, c', c'' the most anterior, or cephalic, lobes. The right anterior is divided into two lobes (c, c'), the left is single (c''); d, trachea, or windpipe.

In the majority of the lungs examined in the laboratory of the bureau which were affected with contagious pleuropneumonia the principal lobes (a, a') were primarily affected.