Leukemia of the Fowl. 3 
areas. Butterfield, in comparing the histological findings in Mohler’s 
cases with his own, finds a convincing similarity between, or identity 
of, the infiltrating cells. In Mohler’s cases, the infiltration was more 
diffuse and not so regularly arranged about the portal tissue. Above 
all, the white blood cells were markedly increased in all the blood- 
vessels, from the intraacinar capillaries to the largest veins. The 
predominating white cell was indistinguishable from the cells in the 
tumor masses of both these and Butterfield’s cases. From the fore- 
going, Butterfield felt justified in granting “the existence of a 
leukemic and aleukemic lymphadenoid hyperplasia in hens.” 
Butterfield and Mohler deserve the credit of showing that leukemia 
occurs in the fowl. Their studies were limited to post-mortem 
findings. 
To Warthin,’ in 1907, we are indebted for the first complete study 
of this disease in fowls. He had the good fortune to secure a living 
animal, which he kept under observation for two and a half months 
before it died. During this time he had an opportunity of care- 
fully studying the clinical course. The blood showed a great reduction 
in the total number of red blood cells. These varied greatly in 
size and shape, and contained less hemoglobin than normal. The 
total number of white cells was greatly increased. Differential counts 
showed a striking increase of the “large lymphocyte” at the ex- 
pense of the other cells of the normal blood. Numerous mononuclear 
forms of the eosinophiles, cells abnormal to the blood, were seen. 
From the blood changes Warthin felt justified in making a diagnosis 
of “lymphatic leukemia of the large cell type.” A careful autopsy 
revealed the following findings: The liver was greatly increased 
in size and was pale yellow in color. The spleen and kidneys were 
also enlarged; both showed numerous yellowish spots from pin- 
point to pin-head in size. In the hemolymph nodes small yellowish 
nodules were found. The bone-marrow appeared as solid plugs, red- 
dish-yellow and friable. The tissue changes were summarized as 
follows: (1) Tumor-like nodules and infiltrations of lymphoid cells 
in all the organs, particularly in the liver, spleen, kidneys, bone- 
marrow and hemolymph nodes; (2) replacement of the normal white 
cells of the blood by cells of the large lymphocyte type, more or less 
atypical in character, but identical with cells in the tumor masses. 
From the findings, both in the blood and in the tissue, Warthin made 
the diagnosis of leukemic lymphocytoma. 
