434 Cha;pter XIV 



and is always followed by immunity. Even in erysipelas, a disease 

 [455] where the relapses are so frequent that certain individuals are, so to 

 speak, predestined to re-acquire it at short intervals, an immunity is 

 produced, but a very transient one. Since the discovery of the strepto- 

 coccus of erysipelas by Fehleisen^, this observer, and several other 

 investigators, have inoculated it into persons affected with malignant 

 tumours. In the course of a series of experimental cases of treat- 

 ment it was noted on several occasions that after a first inoculation, 

 followed by typical erysipelas, a period of immunity was developed, 

 during which the introduction of the streptococcus produced no 

 result. It has also been observed that recurrent fever, when 

 inoculated into monkeys, sets up a very transient but real re- 

 fractory condition. In fibrinous pneumonia, also, the relapses are 

 generally separated by periods of immunity, of longer or shorter 

 duration. 



It was generally supposed that an attack of malarial fever was 

 not only not followed by any immunity, but that a first attack 

 predisposed the organism to a second. Facts of this kind have 

 often been observed and cannot now be questioned. ]N'evertheless, 

 an acquired immunity against malaria is developed under certain 

 conditions. During his travels in Xew Guinea, Koch^ found that in 

 certain regions whilst most children below ten years of age are 

 attacked by malaria, and Laveran's parasite can be demonstrated in 

 their blood, older children and adults are completely immune from 

 this infection. Koch is convinced that in this instance we have an 

 example of immunity acquired by natural means as the result of an 

 attack of malaria at the younger age. This great observer bases his 

 conclusion on the fact that unattacked adults, coming from districts 

 where the children contain the parasite, do not contract malaria when 

 they migrate to other malarial regions, whilst natives coming into 

 these same regions from districts where malaria does not exist are 

 soon attacked. Max Glogner^ has attempted to explain these facts 

 established by Koch, on the assumption that the unaffected adults 

 simply benefit by their natural immunity and that we have here 

 a kind of selection : the adults who are susceptible to malaria die as 

 the result of this disease, whilst others, naturally refractory, resist and 

 [456] show themselves incapable of contracting the disease even in other 



1 "Die Etiologie des Erysipels," Berlin, 1883. 



* Deutsche med. Wchnschr., Leipzig, 1900, SS. 781, 801. 



3 jr^r chow's Archiv, 1900, Bd. clxii, S. 222. 



