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Scientific Proceedings (91). 



be normal or slightly increased, even though the output of the 

 bone-marrow factory may be far above normal. Still another 

 possibility must be conceived, namely, that leucocytes may be 

 formed in some other organ than the bone marrow, for example, 

 the spleen. Dr. F. A. Evans, working in our laboratory, pointed 

 out several years ago that the gray, acute splenic tumor of lobar 

 pneumonia contained large numbers of cells of the myeloid series, 

 as indicated by the oxydase reaction, and suggested that the spleen 

 might be the source of certain of the cells of the pneumonic exudate. 



In the present study, an attempt has been made to correlate 

 the bone-marrow changes and the blood picture in twenty fatal 

 cases of lobar pneumonia, which have come to autopsy. In nearly 

 all of the cases, several leucocyte counts were made. In the 

 majority, there was a record of a count on the last day of the 

 patient's life. Specimens of bone marrow were taken from the 

 upper third of the femur in all cases, and paraffin sections studied 

 after hematoxylin-eosin and Giemsa stain. The result of the 

 study may be summarized as follows: 



A close parallelism in the leucocyte count and the degree of 

 hyperplasia of the marrow was found in only about half of the 

 cases. A few showed a relatively inactive or aplastic marrow, 

 with a leucocyte count well above normal. On the other hand, 

 there were several cases in which the leucocyte count was con- 

 sistently low during life, but in which a markedly hyperplastic 

 marrow was found at autopsy. 



To explain aplastic marrow in the femur (a condition probably 

 common to all the long bones in these cases) associated with a 

 leucocytosis, we may assume either a hyperplasia of the marrow 

 of the flat bones only, or a formation of leucocytes outside the 

 marrow, most probably in the spleen. The second explanation 

 we consider the more plausible. The cases of marked hyper- 

 plasia of the marrow with low leucocyte count are not easily inter- 

 preted. We could not find evidence in these cases of such rapid 

 spread of the lesion as would account for a low leucocyte count 

 through an excessive draining of these cells out of the circulation. 



