Leukaemia of the Fowl, 9 



second, the blood is characterized by a predominance of small and 

 large lymphocytes (90 per cent of the total number) occurring in 

 association with a pronounced lymphomatosis (numerous infiltrations 

 with lymphoid. cells) of the organs. Of interest is the fact that a 

 myeloid type may occur in one generation and a lymphatic in the 

 next, or that both types may occur in the same generation. The 

 occurrence of both types in the same stock suggests very strongly 

 that both forms of leukaemia in man are due to one and the same 

 infection. 



II. STUDIES ON THE NORMAL FOWL. 



With the hope of making the findings in the leukaemic animals more 

 clear, the following brief data of the normal fowl are presented. These 

 are limited to those portions of the body which are involved in 

 leukaemia. They are compiled from a large number of chickens. 



EXTERNAL APPEARANCE. 



Healthy, young, adult Plymouth Eock hen. Comb, featherless 

 area about eyes, and wattles bright red. Conjunctivae and buccal 

 mucous membrane pink. Skin of body white with a faint yellow 

 tint. Well nourished, sides of sternum covered with a thick pad of 

 tissue, ribs not palpable. Average rectal temperature, 42 C. 



BLOOD. 



The blood for counting and smears was obtained from the vein under 

 the wing, which always appears to be well filled. From a small needle 

 puncture the blood flows under pressure, is thick, dark red and clots 

 quickly. 



Blood-count. The nuclei-containing red blood cells of the fowl 

 make it practically impossible to count the white blood cells by the 

 usual direct method. After laking the former, one cannot differ- 

 entiate between the nuclei of the two types of cells. It was there- 

 fore necessary to resort to the indirect method, t. e., to determine the 

 proportion of white to red cells from a stained smear, count the total 

 number of cells, both whites and reds, by the direct method, and then 

 calculate the total number of each present. 



The red blood cells vary somewhat : lowest limit, 2,500,000 ; highest, 

 4,500,000 ; average, 3,000,000-4,000,000 per c. mm. White blood cells : 



