302 BLOOD AND BLOOD EXAMINATION 



total number we speak of as hyperleukocytosis, and a diminution, as hypoUu- 

 kocytosis. [I prefer the term " leukocytosis " for an increase, and the term 

 "leukopenia" for a decrease, in the circulating leukocytes. — Ed. J Eyen at 

 the normal, the absolute number of white blood-corpuscles and the propor- 

 tion of their different varieties show distinct variation ; in different pathologic 

 conditions, however, and especially in infectious diseases, the deviation of these 

 conditions from normal becomes more marked. We find the explanation for 

 this in the principle of chemotaxis, according to which bacteria and their 

 products of metabolism, as well as numerous other toxic substances, are capa- 

 ble of attracting by chemical irritation the cells which have accumulated in 

 the blood-forming organs, a condition which we designate as positive chemo- 

 iaxis; on the other hand under quite similar circumstances the leukocytes are 

 repelled by the previously mentioned poisons, so that the number in the cir- 

 culating blood is decreased, and this process we call negative chemotaxis. 

 The self-evident presupposition for this attraction and repulsion of the leu- 

 kocytes (since the condition is a notable example of action at a distance) is the 

 property of the leukocytes to show active movement. For this reason we give 

 to this state the name active leukocytosis. 



Active leukocytosis furnishes the most varied pictures, not only quantita- 

 tively but qualitatively, because of the fact that the chemotaxic irritability of 

 the different leukocyte varieties shows speciiic differences. Thus there are 

 substances which only influence one variety of cell in a positive chemotaxic 

 manner, being inert toward all others. This shows itself most frequently in 

 a decided increase of the polynuclear neutrophilic leukocytes alone in numer- 

 ous infectious conditions, as in septic diseases, diphtheria, and articular rheu- 

 matism ; other infections have a negative chemotaxic property for this -cell 

 form so that, for example, in enteric fever, we often find them decidedly 

 diminished. On the other hand the eosinophilic leukocytes show marked 

 power of attraction for the blood in bronchial asthma, in pemphigus, in trichi- 

 nosis, and in several varieties of helminthiasis. More rare, but nevertheless cer- 

 tain, is a chemotaxis of the mast-cells exhibited according to this principle. 



It is a peculiarity of the chemotaxic reaction that all leukocytes endowed 

 with one type of granulations are attracted simultaneously even if the com- 

 position of the nucleus varies ; for example, the myelocytes react iir the same 

 way as the polynuclear neutrophilic leukocytes. For this reason, in accord- 

 ance with the variety of the cell that is influenced, we speak of neutrophilic 

 hyperleukocytosis or hypoleukocytosis of eosinophilic or mast-cell leukocytosis. 



Besides these specific leukocytoses, we diagnosticate another form of hyper- 

 leukocytosis which we designate as a mixed form, because in this all cells that 

 are capable of chemotaxic reaction are increased in the blood. This is 

 myelogenous leukemia; we therefore arrive at the hjqjothesis, no matter how 

 obscure to us the etiology and pathogenesis of myelogenous leukemia may 

 still be, that in this disease a toxic substance is active which has the property 

 of influencing all myelogenous cell varieties in a positive, chemotaxic manner. 



A form of white blood-corpuscles must still be mentioned which does not 

 possess the active property of locomotion: these are the lymphocytes. [See 

 note at foot of p. 298.] It is therefore evident that this form is not subject to 



