DIAGNOSTIC. APPLICATIONS OF THE BLOOD-COUNT 2ig 



corpuscles and a great reduction of the hsemoglobin ; the colour- 

 index falls, therefore, and 0-5 may be taken as an average, 

 though much lower figures occur. The corpuscles are pale, but 

 abnormal forms are rare. Normoblasts are very rare, but when 

 they occur usually herald a rapid improvement. The leucocytes 

 are normal in numbers, or there may be leucopenia. 



It may be confounded with various forms of secondary anaemia, 

 but in them the colour-index is usually higher, and the leucocytes, 

 especially the polynuclears, tend to be increased. 



Myelogenous Leucocyth^mia (" spleno- medullary"). —There 

 is an enormous increase in leucocytes, which in an average case 

 may amount to 400,000. All varieties of leucocytes are increased 

 in absolute numbers, but the increase mainly affects the poly- 

 nuclears and the eosinophiles ; the lymphocytes are relatively so 

 scanty that they may be difficult to find. In addition, there are 

 abnormal cells : eosinophile myelocytes and large cells with 

 basophile granulations, cells occurring in practically no other 

 disease, and both Ehrlich's and Cornil's myelocytes. 



There is usually anaemia of the secondary type, and normoblasts 

 are numerous. 



The whole picture is most characteristic, and can hardly be 

 mistaken for anything else. 



Lymphatic Leucocyth.emia. — There is no difficulty in the 

 recognition of a typical case of chronic lymphatic leucocy- 

 thsemia ; the leucocytes are enormously increased (100,000 to 

 1,000,000), and consist almost entirely of lymphocytes (often up 

 to 99 per cent.) : in many cases the large forms predominate. 

 There is also a varying degree of secondary anaemia. 



In an adult these appearances are quite characteristic, but in 

 childhood similar counts may be seen in a variety of conditions, 

 such as hooping-cough, broncho-pneumonia, etc., though it is 

 rare to find a figure as high as 100,000. 



In some acute cases of lymphatic leucocythaemia similar 

 appearances occur. In others the increased percentage of 

 lymphocytes is present, but not the total increase ; thus, in one 

 case fatal in a few weeks I never found more than 10,000 

 leucocytes, in which the lymphocytes varied between 76 per cent, 

 and 100 per cent. These cases are very difficult to diagnose 

 from acute tuberculosis of the lymphatic glands. In the latter 

 case the total count may be expected to be low, in the former 

 slightly raised ; in tubercle the percentage of lymphocytes rarely 



