CORYNEBACTERIUM DIPHTHERIA. 401 



1. By treating first with slightly virulent and later with 

 highly virulent cultures of diphtheria bacilli. 



2. By the injection of diphtheria toxins in small quan- 

 tities or toxins partially weakened by heat, and following 

 with larger quantities. This is repeated with increasing 

 doses. 



3. By injection of serum from an animal immunized 

 against diphtheria. 



Also, in man, prophylactic injection of immune serum 

 has been employed when there was danger of diphtheria, 

 in part with very good results. See, for example, Slawyk 

 (C. B. xxiv, 396). Regarding the almost universally 

 acknowledged success of the antitoxin injection for thera- 

 peutic purposes in cases of disease, it is not necessary to 

 enter into details here. 



Special Diagnosis of the Coryn. Diphtheriae. 1 

 From the suspected material the following smear prepara- 

 tions are made : 



1. Staining with methylene-blue or dilute fuchsin with 

 a little warmth. 



2. A preparation stained by Gram's method often pre- 

 sents the diphtheria bacilli more plainly, since the con- 

 taminating bacteria are in part unstained. 



3. Granule staining by Neisser's method. 



If there are found, in this way, abundant and especially 

 long forms stained in segments with characteristic cross 

 arrangement and many granules, then the diagnosis of 

 diphtheria is to be considered as very probable. 



To render the diagnosis more secure, delicate smear in- 

 oculations are made upon ascites-agar, by drawing the 

 needle five or six times in succession over fresh parts of 

 the nutrient medium. The cultures thus obtained corre- 

 spond either to the typical picture of the diphtheria bacil- 

 lus, with its growth of moderate intensity, or we obtain 

 meager c ' xerosis-like ' ' or luxuriant ' ' pseudodiphtheria- 

 like" cultures. 



1 Bruno (Berl. klin. Wochenschr. , 1898,1127) attempted to make 

 use of serum diagnosis here also. Diphtheria serum produced aggluti- 

 nation of certain diphtheria cultures, but not all. It was not sufficient 

 to separate diphtheria and pseudodiphtheria. 



