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The " active " form of leucocytosis is divided by Ehrlich 

 into the following groups : — 



A. Poiynuclear leucocytosis. 



1. Poiynuclear neutrophil. 



2. Poiynuclear eosinophil. 



B. Mixed leucocytosis, " myeljemia." 



The subject of leucocytes covers too large an area for one 

 to attempt, even in the most sketchy way, to deal with it 

 adequately. I shall, therefore, give one or two examples of 

 each of the above divisions. 



First, the poiynuclear " neutrophil " leucocytosis. This 

 is called by some, Ewing, for example, an " inflammatory 

 leucocytosis," and is present in the majority of febrile 

 infectious diseases, typhoid fever and measles being two 

 notable exceptions. 



When a patient is attacked by pneumonia the 

 pneuinococcus or microorganism, which is the ultimate cause 

 of the disease, pours out a toxin into the blood. This toxin 

 acts on the marrow in a specific manner. The marrow- 

 responds to this stimulus by an increased outflow and 

 production of the poiynuclear " neutrophil " cells. 



It is the duty of these cells to meet and counteract the 

 poison of the pneumococcus by producing an antitoxin, and 

 also, possibly, to digest the cocci themselves. In favourable 

 cases the leucocytosis reaches 20,000 or 30,000 per cubic 

 millimeter. If, however, the poison is very virulent the marrow 

 may fail to respond, and there is no increase in the number of 

 the white cells in the blood. It is then said that the patient has 

 re-acted badly and the outlook is grave. Shortly before the 

 crisis the leucocytosis begins to diminish, and during the drop 

 in the number of the poiynuclear " neutrophils " there is an 

 increase in the number of the coarsely granular eosinophil cells. 

 This contrast in the response of the two forms of poiynuclear 

 cells is most interesting and is noted in many of the 

 inflammatory leucocytoses. 



