Leukemia of the Fowl. 17 



Peritoneal Cavity. Omental fat entirely absent. Lower margins of 

 right and left lobes of liver extended almost to the pubes, i. e., far 

 below xiphoid. 



Liver. Enormous. Dimensions and weight not taken. Its surface 

 was extremely mottled. It was reddish brown and specked with 

 innumerable gray or slightly yellow spots from a pin-point to a few 

 millimeters in diameter, frequently closely packed to form irregular 

 areas, the largest 1 cm. in diameter. In addition there were scat- 

 tered gray or slightly yellow nodules, averaging about 2 mm. in 

 diameter. Sectioned surface similar in appearance. The blood-vessels 

 were surrounded by a gray zone. 



Spleen. Enormous. Dimensions and weight not taken. It was 

 about the size of a small hen's egg. Diffusely gray. 



Heart. At the apex there were several gray spots, pin-point in size. 



Kidneys. Greatly enlarged. Both showed nodules, similar to those 

 in liver. 



Bone-marrow. Abundant, gray, with absence of fat. 



Thyroids, Parathyroids, Lungs, Gastro-intestinal Tract, Pancreas 

 and Adrenals. Apparently uninvolved. 



MICROSCOPICAL . EXAMINATION. 



Cervical Lymph-glands. The normal structure was somewhat 

 changed. There was complete disappearance of the interlobular fat 

 with approximation of the greatly swollen parenchymatous lobules. 

 Here and there were intra- and inter-lobular foci of myeloid tissue. 

 These frequently enclosed an artery or vein. There was also a more 

 diffuse infiltration of the parenchyma by myeloid cells, filling capillaries, 

 veins, arteries and in places breaking through the lobular capsule into 

 the interlobular tissue. Of the infiltrating cells two predominated : (1) 

 A large mononuclear, usually round, at times slightly polygonal due to 

 pressure, with a single, round, oval, or indented, vesicular, at times 

 multiple, nucleus with one or more nucleoli. Its cytoplasm was non- 

 granular and slightly basophilic. (2) The mononuclear myelocyte 

 with eosinophilic granules, described under normal bone-marrow. 

 Mitoses of these two cells were quite common. Normoblasts and 

 megaloblasts appeared to be present. 



Liver. Here the process was most extreme. Very little liver tissue 

 remained. Everywhere were closely packed masses of myeloid cells 

 from which the liver trabeculae had completely disappeared. These 



