92 IMMUNE SERA 



possess specific haemolytic properties for certain 

 cells, and later on may lose this property entirely. 

 In human serum these same individual and periodic 

 variations may be demonstrated, as Wassermann 

 was able to prove experimentally. However, the 

 circumstances on which these variations depend are 

 as yet entirely unknown to us. Possibly we are 

 dealing here with subtle pathological changes. 



Source of the Complements Leucocytes as a 

 Source Other Sources. Where do the comple- 

 ments or alexins originate? This question has been 

 studied particularly by MetchnikofI and by Buch- 

 ner; also by Bail, Hahn, Schattenfroh, and others. 

 These investigators believe that the leucocytes are 

 the source of the complements or alexins. There 

 is, however, this difference between the views 

 of Metchnikoff and Buchner: whereas Buchner 

 believes the alexins to be true secretory products, 

 Metchnikoff believes that they originate on the 

 breaking up of the leucocytes, i.e., that they are de- 

 composition products. Metchnikoff bases his belief 

 chiefly on the work of his pupil, Gengou, who showed 

 that although the serum was rich in alexin (i.e., com- 

 plement) the plasma contained none at all. 



Other authors, as Pfeiffer and Moxter, as a result 

 of their experiments, are not willing to assume the 

 existence of any relationship between the alexins 

 and the leucocytes. Gruber as well as Schatten- 

 froh are ready to believe the leucocytes to be the 



