BACTERIOLOGICAL EXAMINATION 303 



the laws of chemotaxis. Since, in spite of this, there are often transitory or 

 permanent variations in the number of lymphocytes found in the blood, these 

 require another explanation. We find this either (a) in the increased pro- 

 duction of lymph-cells, due to hyperplasia or inflammation of the lymphatic 

 tissue, or (6) in an influx of this variety of cells by increased lymph circula- 

 tion. The lymphocytes themselves are entirely passive in these processes, and 

 for this reason we designate their increase as passive Uulcocytosis. Extreme 

 degrees of this condition we designate as lymphatic leukemia. (A special de- 

 scription of the various forms of leukemia will be found in this volume, the 

 article being by Professor v. Leube.) 



I cannot close this article without showing by a few examples that the 

 researches described here are of importance in the diagnosis of diseases other 

 than the actual blood diseases. 



The number of the leukocytes, for instance, is decidedly important in the 

 differential diagnosis of the infectious diseases. If we remember how diffi- 

 cult the differentiation of enteric fever from other affections occasionally is, 

 any sign which facilitates the diagnosis will be a great help. The affections 

 which may be confounded with enteric fever, such as osteomyelitis, general 

 sepsis, pneumonia, etc., are characterized by a decided increase of the neutro- 

 philic leukocytes, while in uncomplicated typhoid fever this variety of cell is 

 decidedly diminished or is at most present in only normal numbers. 



In the differentiation of inflammations of the cerebral meninges, an ex- 

 amination of the blood may often be of benefit ; and if, in a case of undoubted 

 meningitis, we find a normal relation of the leukocytes, the assumption of the 

 tubercular form instead of a purulent one is justified. 



The occasionally extremely difficult differentiation between scarlatina and 

 measles may often be facilitated by a blood examination owing to the fact that 

 a distinct diminution of the polynuclear leukocytes, or an almost normal con- 

 dition of the same, is quite characteristic of measles, while in scarlatina a 

 decided polynuclear neutrophilic hyperleukocytosis is the rule. 



Lately Curschmann and subsequent investigators have reported that in 

 numerous cases of perityphlitis, the diagnosis of an abscess which could not 

 be determined by palpation was made from an increase of leukocytes to 20,000 

 and more, and this prevented all necessity for exploratory incision. [" Lately " 

 the Germans have wakened up to these facts which have been known and used 

 in America since described by me in 1894. — Ed.] The subsequent surgical 

 operation absolutely confirmed the reliability of this symptom. On the other 

 hand, clinicians have in numerous cases discountenanced a surgical operation 

 on account of an almost normal leukocyte finding. Here, also, the further 

 development of the disease justified the diagnosis. Almost as much impor- 

 tance may be ascribed to the phenomenon of leukocytosis in the diagnosis of 

 abscesses localized elsewhere, which otherwise could not be determined with 



certainty. 



In a case in which the diagnosis was otherwise obscure, Brown concluded 

 from a decidedly marked eosinophilic hyperleukocytosis that the underlying 

 condition was trichinosis; the further course of the disease justified this 

 opinion. 



