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drawback of the delay is exceeded by the benefit of the greater 

 correctness. 



The characteristics which have to be considered, are those 

 of the acid-production out of carbohydrates, the behaviour 

 toward serological reactions and the power of producing toxin 

 (virulence). 



As long as there has been difference of opinion as regards 

 the identity of the diphtheria bacillus the production of acid 

 has played its part. Now ordinary broth was used, then again 

 different carbohydrates were added, in most cases glucose-broth 

 was employed. Some thought the acidproduction to be of 

 difïerential-diagnostical value, others looked upon the amount 

 of acid produced as a thing of great importance. 



Of late little attention has been paid to the results obtained 

 by this method, only recently Miss VAN RiEMSDIJK in the 

 »Centrallblatt für Bakteriologie« brought the acidproduction out of 

 glucose into prominence again. For this examination she made 

 a good simplification of the culture-medium by using a pepton- 

 solution and adding glucose and litmus. She looks upon this 

 qualititive reaction as an important diagnosticum for the diffe- 

 rentiating of diphtheria and pseudo-diphtheria. 



It seemed very important to me, to investigate if by this 

 method it would be easy to sort out our practical material. I 

 expected that all diphtheria bacilli we diagnosed would produce 

 acid in this medium. Miss Smit was so kind as to examine 

 one hundred pure cultures, isolated by her without making any 

 choice whatever. Under these lOO strains only one did not 

 produce acid and this was a bacillus, which looked suspicious 

 by the the routine examination too. 



For the working out of our practical material the acid-pro- 

 duction does not give information of practical importance, so 

 that I have not been able to find a reason why to extend our 

 daily examination in this way. Against the drawback of the 

 decision being delayed for one, or as a rule for more days, there 

 is to my mind no sufficient advantage. 



In the second place I mentioned the serological reactions, 

 which might be useful to the extension of the working-methods. 

 From what has been said above it may be concluded, that in 

 my opinion none of these reactions give sufficiently reliable 



