Leukcemia 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 1.5 x 8 x 4 cm. and 2 x 1 x .5 cm., 

 respectively. They appeared uniformly gray. The lobules of the par- 

 enchyma were enlarged and the interlobular fat had disappeared. In a 

 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 leuksemic 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 leukaemic 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, 



