Leukemia of the Fowl. 25 
branes were always very pale. The eyes, nose and mouth were never 
involved. There was extreme emaciation, and great scarcity or entire 
absence of subcutaneous fat. Muscular atrophy was usually marked, at 
times practically only the skeleton remained (Fig. 5). 
Cervical Lymph-glands.—Macroscopically, these were usually unin- 
volved. In two cases they were definitely enlarged (Fig. 3,a and b), in 
the one very much so, measuring 1.5x8x4 cm. and 2x1x.5 cm., 
respectively. They appeared uniformly gray. The lobules of the par- 
enchyma were enlarged and the interlobular fat had disappeared. Ina 
third case, they were of normal size and appearance, but showed several 
gray nodules, 1 mm. in diameter. Microscopically, those glands which 
appeared normal in gross were usually free from myeloid infiltration, 
although their blood-vessels contained leukemic blood. The diffusely 
enlarged glands showed a marked swelling of their parenchyma, with 
complete atrophy of the interlobular fat. Myeloid cells, both the large 
mononuclear and the mononuclear myelocyte with eosinophilic granules, 
were scattered through the lobules. Foci, some composed entirely of 
the first, and others exclusively of the second, were localized principally 
in the interlobular connective tissue. They were rich in mitotic figures. 
The gray nodules seen in gross proved to be masses of proliferating 
myeloid cells. All the blood-vessels were filled with the characteristic 
blood. 
Thyroids and Parathyroids.—These were grossly and microscopically 
uninvolved, with the exception of the blood-vessels, which were filled 
with leukemic blood. 
Peritoneal Cavity—In every case the omental fat was greatly de- 
creased. At best, it was present only in moderate amount. As a rule 
it was replaced by a thin yellow membrane. Ascites occurred in six out 
of 13 cases, at times in sufficient quantity to distend the abdomen. It 
was always associated with a sero-fibrinous mass, which covered not only 
the liver and most of the other abdominal viscera, but also spread over 
the outer surface of the pericardium. 
With enlargement of the liver, the lower margins of its two lobes 
change their position in relation to the tip of the xiphoid. They 
descend to this landmark and frequently extend far beyond. With the 
exception of Nos. 31 and 70, every animal of the 13 had an enlarged liver 
(Table 1). The margins of the right and left lobes of the smallest of the 
enlarged livers were, respectively, 1 and 3 cm. above the xiphoid, while 
the margins of the largest liver extended 3.5 and 3 cm., respectively, 
