238 NORMAL AND PATHOLOGICAL BLOOD 



Megaloblasts are practically never seen, except in some of the very severe para- 

 sitic anaemias, as the broad Russian tape-worm infection. The red cells generally 

 number between 2,000,000 and 4,000,000, thus differentiating chlorosis. The 

 leukocytes are frequently increased to 15,000. In the anaemia of splenic anaemia 

 there is a marked leukopenia. In anaemias from malignant tumors the color index 

 is usually of the chlorotic type the haemoglobin content of the red cells being more 

 affected than the number. Normoblasts are usually present, and this finding may 

 differentiate gastric cancer from ulcer. In bone marrow metastases megaloblasts 

 may be expected. Myelocytes and so-called tumor cells (large cells with faintly 

 staining vacuolated nuclei and but little cytoplasm) may also be found. As a rule, 

 there is a moderate leukocytosis in malignant disease. Eosinophiles may be largely 

 increased in sarcoma. 



THE LEUKAEMIAS 



It is in the leukaemias that we have the greatest increase in the num- 

 ber of white cells. These cases show more or less anaemia, but we may 

 have cases of myelogenous leukaemia showing 250,000 leukocytes per 

 cubic millimeter without particular change in the red cells. The more 

 marked the red-cell change the more severe the condition. 



There are two well-defined types of leukaemia, the lymphatic and the spleno- 

 myelogenous. It must be borne in mind, however, that while a greater change in 

 the lymphatic glands may produce the lymphatic type, yet even in such cases we 

 expect to find alteration in bone marrow and spleen; that is, there is a general involve- 

 ment of the haemopoietic system in all leukaemias, the activity being most marked in 

 spleen and bone marrow in certain cases and in lymphatic glands in others. 



Myelogenous leukaemia is a very rare disease, about five times as 

 rare as pernicious anaemia. Lymphoid leukaemia is still more rare. 



Splenomyelogenous Leukaemia (myeloid leukaemia). The differen- 

 tiation of the blood picture of this disease from leukocytosis does not 

 depend on the number of leukocytes, but on the presence and large 

 proportion of myelocytes. We expect both neutrophilic and eosino- 

 philic myelocytes in myeloid leukaemia the proportion of these varies, 

 but, as a rule, the neutrophilic one is the common one. The blood in 

 advanced cases is milky and shows a most marked buffy coat. The 

 marrow is largely replaced by a yellow pyoid material. The spleen 

 may weigh 10 pounds. 



The leukocyte count is on the average from 200,000 to 500,000. Cases are re- 

 ported of more than 1,000,000 white cells. The neutrophilic myelocytes make 

 up about 30 to 40% of these and, about equal in number, are found the polymor- 

 phonuclears, while the percentage of the lymphocytes is decreased (2 to 5%) and 

 normal eosinophiles, eosinophilic myelocytes, and large mononuclears make up the 

 remaining percentages. We usually have great numbers of normoblasts. Megalo- 



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