mycobacteriacEjE: the bacillws of diphtheria 



303 



be only a mild reddening or it may be a widespread area of 

 necrosis. Most frequently there is an exudate of plasma con- 

 taining leukocytes, epithelial cells and bacteria, and this coagulates 

 on the mucous surface. The epithelium underneath also under- 

 goes necrosis in moderately severe cases and is firmly attached to 

 the exudate by the fibrin threads. In severer 

 forms there is an escape of blood into the exudate 

 giving it a dark color. The local lesion is largely 

 due to soluble toxin formed by the bacilli. The 

 general disturbance is, as a rule, due solely to the 

 absorbed toxin. The bacilli remain at the site of 

 the lesion and do not appear in the blood or in- 

 ternal organs in any appreciable numbers. They 

 are occasionally found in the spleen or kidney of 

 fatal cases, but not more frequently than the 

 streptococcus is found in these organs in ap- 

 parently uncomplicated fatal cases of diphtheria. 

 The local lesion in the throat may be simu- 

 lated very closely by inflammation due to 

 streptococci, but the general manifestations are 

 not duplicated in such conditions. Mixed in- 

 fection with diphtheria bacilli and virulent used in the diag 

 streptococci may present a clinical picture of ^"^'^ ^he pledget 

 great severity. Bacteriological examination is °^ cotton on the 



. . wire shown is 



often a great help m diagnosis even to the expert much too bulky. 

 clinician, and is quite generally employed. 



Bacteriological Diagnosis of Diphtheria.— Ixx many large cities 

 the bacteriological diagnosis of diphtheria is undertaken by 

 boards of health. The methods used differ somewhat in detail, 

 but are similar in the main, and are based upon the procedure 

 devised by Biggs and Park for the Board of Health of New York 

 City. Two tubes are furnished in a box. The tubes are like 

 ordinary test-tubes, about three inches in length, rather heavy and 

 without a flange. Both are plugged with cotton. One contains 

 slanted and sterilized LofQer's blood-serum mixture (Fig. 125); 



Pig. 125. — Swab 

 and culture-tube 



