A 



mong the means we have at our disposal lor the 

 study of the nature of the immunity, comparatively 

 little attention is paid to the investigation of the 

 increase and the decrease of antibodies during different 

 modes of immunisation. From different points of view 

 this is rather curious. From a theoretical one, because 

 the study of this phenomenon seems to give valuable 

 information about what is going on in the organism 

 during the immunisation; from a practical point of 

 view, because under the immense production of anti- 

 toxic sera, which is now going on the whole world 

 over, it is of great economical interest to know as 

 exactly as possible, at what moment the highest 

 amount of antibody may be expected. It is a well 

 known fact, that Brieger and Ehrlich 1 ) showed the way 

 by their demonstration of the undulatory course of the 

 antitoxin in the case of a goat, immunised against te- 

 tanus. In a more extensive series of experiments Salo- 

 monsen and Madsen 3 ) thereafter showed that pheno- 

 mena quite analogous occurred in the case of horses 



!) Brieger und Ehrlich: Bcilriige zur Kenntniss der Milch immunisirler Thierc. 



Zeitschr. f. Hygiene etc. XIII. 1893. 



'-) Salomonsen et Madsen: Kecherches sur la niarche de 1'imniunisation active 

 centre la diphtcrie I. Annales de 1'Instilut Pasteur 1897. 

 II. 1899. 



Om Forskelligheder i Serums antidiphtheriske Styrke hos aktivt 

 i in mun isercde Heste. N'ordisk Mcd. Arkiv 1897. Festhand for Axel Key. 



3 



