316 



COLLECTED STUDIES IN IMMUNITY. 



I believe this demonstrates that the horse immune serum em- 

 ployed by me for therapeutic purposes, meets the requirements which 

 are nowadays to be demanded of a bactericidal immune serum, 

 namely, (1) that it be high grade, and (2) that it find a fitting com- 

 plement in normal human serum. This is the first serum employed 

 in human therapy which fulfils the conditions laid down by Ehrlich 

 in hisCroonian Lecture, 1900. The excellent curative results obtained 

 by me in Japan l furnish abundant confirmation of the correctness of 

 Ehrlich 's views. 



As already mentioned, the phenomenon of deflection of comple- 

 ment could be demonstrated very prettily with the complement of 

 this active horse serum. Since this deflection is primarily dependent 

 on the amount of immune body present, it may perhaps be possible to 

 employ the degree of deflection as a measure of the titer of a serum. 

 Some experiments in this direction which I have undertaken at the 

 suggestion of Prof. M. Neisser have not yet been concluded. 



I have already stated that the other active sera (e.g. goat serum, 

 etc.) could not be used for complementing the dysentery immune 

 serum, although in themselves they were bactericidal. But for this 

 immune serum the phenomenon of complement deflection can be 

 demonstrated very nicely with these sera also. (See Table III.) 



TABLE III. 



Perhaps also this method of testing is available for determining 

 the grade of bactericidal sera. 



Furthermore by means of an absorption test analogous to the 

 experiments of A. Lipstein 2 I have convinced myself that the deflec- 



1 Deutsche med. Wochenschrift, 1901, Nos. 43-45. 



2 See pages 132 et seq. 



