LEUKEMIA 91 



size though there is often a considerable increase in the reticular 

 connective tissue. 



Any or all of the lymph glands may be enlarged. In the en- 

 larged lymph glands there is a diffuse hyperplasia of lymph cells, 

 so that the distinction between follicles and lymph cords is lost. 

 The reticulum is often obscured by the great mass of lymphocytes. 

 The walls of the blood vessels are composed of collections of lym- 

 phocytes which sometimes break through into the lumen. In 

 many cases a few myelocytes are found in the lymph sinuses. The 

 capsule is often infiltrated with lymphocytes. 



In the liver the capillaries are widened and contain many lym- 

 phocytes. The interlobular tissue is infiltrated with lymphocytes 

 as circumscribed growths or as a more or less diffuse infiltration. 

 Sometimes a reticulum may be distinguished in these masses of 

 lymphocytes; often the reticulum is obscured by the mass of cells. 



Masses of lymphocytes occur in other organs, as the kidney, 

 skin, serous membranes, central nervous system, etc. They appear 

 as small grayish nodules, composed of lymphocytes arranged as 

 in the organs described. 



Occurrence. Leukemia has been observed in the domesti- 

 cated animals in comparatively few cases. Nocard, in 1880, cited 

 43 cases, nine in horses, five in cattle, four in swine, twenty-two 

 in dogs and one in a cat. In the Prussian army from 1890 to 1895, 

 there were 26 horses reported as having leukemia. Other cases 

 are reported, mostly in dogs. The disease is doubtless a rare one, 

 but is probably not so rare as the number of recorded cases would 

 lead one to suppose. All of the cases reported in the domesticated 

 animals in which histological examinations have been made have 

 been of lymphatic leukemia. Authentic cases of mixed-celled leuke- 

 mia have not, so far as I am aware, been observed. In the majority 

 of cases reported, merely the proportion of leucocytes to red cor- 

 puscles, the post-mortem appearances, and the symptoms in part 

 of the cases are given. 



Weil and Clerc reported a case of lymphatic leukemia in a dog 

 weighing 15,500 grams. There were 2,110,000 red corpuscles, 

 320,000 leucocytes and 36% hemoglobin. The differential count 

 of the leucocytes gave lymphocytes and small mononuclears 88%, 

 large mononuclears 3%, polynuclears 8%, and plasma cells 1%. 

 Warthin has reported two cases, Kon has found another and six 



