IMMUNITY. 353 



cities (Peer) ; in Berlin (Gottstein) the 

 mortality from 1880-1894 ranged between 

 23.8 0-46. 5 / . Moreover, the mortality is very 

 different in the different months, and in Berlin 

 it varies enormously according to the district, 

 in some parts of the city sinking even to 9 / . 

 The occurrence of diphtheria was formerly de- 

 termined clinically, and the anginas, the mild 

 cases of throat inflammation, were left out of 

 account. According to Behring, however, the 

 diphtheria serum, because it is obtained by the 

 aid of pure cultures of diphtheria bacilli is 

 effective only against those cases of throat 

 trouble that are provoked exclusively by the 

 Klebs-LofHer bacteria. By adopting this clas- 

 sification the gravest cases of septic diphtheria 

 are excluded. Further, it is asserted that the 

 cases ought to be treated as early as possible. 

 At present the proof of the presence of diph- 

 theria bacilli is sufficient to lead to treatment 

 with the curative serum, in spite of the fact 

 that many cases in which the diphtheria bacil- 

 lus is found never become diphtheria clinically, 

 while on the other hand many cases are re- 

 garded as pseudo-diphtheria which clinically 

 might be called true diphtheria. Under the 

 influence of these three fundamental require- 

 ments, namely, that the diagnosis shall be 

 based solely upon the presence of the 

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