20 MASS. EXPERIMENT STATION BULLETIN 391 



Many myelocytes contained round polychromatophilic granules and some spindle- 

 shaped acidophilic granules (Plate V, Figure 2). Mathews (17) stated that bone 

 marrow taken from any part of the skeleton in his series of cases of myelocytoma 

 showed some neoplastic-like hyperplasia. The bone marrow of the femur was 

 examined in 15 of the cases in this study (in 5 cases no marrow was preserved), 

 and in all there were areas considered to be identical with the extrameduUary foci 

 of neoplasia. In many of the cases examined, the granuloblastic e'ements of the 

 marrow were almost entirely converted to a tissue resembling myelocytoma. 



An infiltration of the mucosa of the intestine, especially in the duodenum, was 

 apparent upon gross examination of two cases. These consisted of small gray 

 masses representing villi swollen with an infiltration of myelocytes. In three 

 other cases, infiltration of the intestinal mucosa was found upon histological 

 examination. 



Data on egg production were available on only three cases of m\'eloc\toma 

 (Table 12). Two of the birds could be considered good producers of eggs and the 

 third was a poor producer. The average production index was 0.610, or slightly 

 higher than that found in cases of lymphocytoma. Egg production ceased, on an 

 average, 21 da\s preceding necropsy of the three cases. 



Table 12. — Data on Egg Production of Chickens with Myelocytoma. 



Productive life is the interval between first and last eggs laid. 

 Production index is the factor obtained by dividing the number of eggs laid 

 by the productive life in days. 



Age at Productive Number of Production Interval from 



Case No. Necropsy Life Eggs Laid Index Last Egg to 



(Days) (Days) Necropsy 



(Days) 



T31 *K 319 133 



T 2426 D 389 105 



T681 D 308 90 



Average 339 109 67 .610 21 



*K indicates that bird was killed for examination; D, that it died. 



Fowl Leukosis 



The collection of neoplasms of the chicken contains 19 cases of fowl leukosis 

 (Plate X, Figures 5 and 6). Both erythroblastic (17 cases) and granuloblastic 

 (2 cases) forms of the disease were found. Since the general pathology of spon- 

 taneous fowl leukosis is well discussed elsewhere, no attempt is made to describe 

 the general pathological findings. The pathology was similar to that of cases 

 previously described (Feldman and Olson 8). 



The average age at necropsy of chickens with leukosis was appro.ximateh' 47 

 weeks, or slightly older than in cases of lymphocytoma (Table 13). The sex 

 distribution was 17 females and 2 males, or a ratio of 8.5 to 1. The average 

 percentage of bod\' weight for the liver, spleen, and kidne\- in 12 cases of leukosis 

 is indicated in Table 13. This value is lower than in cases of hmphocxtoma for 

 the li\"er and kidne\', and slightly higher for the spleen. 



