58 COLLECTED STUDIES IN IMMUNITY. 



The difference between these two views is considerable. According 

 to our views the complement ( = Bordet 's alexin) possesses a direct 

 affinity, due to chemical relationship, to the immune body, while 

 according to Bordet such a relation is excluded. Since this question 

 concerns our scientific understanding of haemolysins and bacterioly- 

 sins, and concerns also a basic difference affecting the practical appli- 

 cation of the bacteriolysins, we shall have to study the subject more 

 closely. 



I. Concerning Alexins. 



Buchner, who by his thorough investigations on the bactericidal 

 and globulicidal properties of normal sera laid the most important 

 foundations of this subject, assumes that the serum contains cer- 

 tain protective bodies, alexins, which act equally on bacteria, foreign 

 blood-cells, etc. These alexins, which are essentially of the character 

 of proteolytic enzymes, 1 are of most unstable (labile) nature and lose 

 their power by being heated to 55 C. Bordet also seems to assume 

 the presence, in normal serum, of alexins in Buchner's sense. 



According to Buchner, the serum of a given species always con- 

 tains the alexin as a single definite substance. Now in our second 

 communication we showed that the matter was much more com- 

 plicated than this ; that in the hsemolysins of the normal sera examined 

 by us the action depends on the combination of two substances 

 which correspond entirely to the two components of the hsemolysin 

 obtained by immunization. Hence an " alexin " also consists of 

 an interbody which withstands heating, and a complement which 

 is generally thermolabile'. 2 The interbody is in every respect the 

 complete analogue of the immune body, and the only difference 

 between these is that in one case the side-chains of the protoplasm 

 are thrust off in the course of normal vital processes, in the other 

 case this is due to an immunizing procedure. 



Since our second communication we have been able to confirm 

 this view by means of a large number of separate cases. Of these 

 we shall mention only a few which serve, above all, to support the 

 immediate consequences of our view, namely, the multiplicity of the 

 hcemolysins of normal serum. 



Goat serum dissolves the blood-cells of rabbits as well as those 



1 Buchner, Munch, med. Wochenschrift, 1900, No. 9. 



2 Moxter (Centralblatt fur Bacteriologie, Vol. 26) has demonstrated this 

 also for a normal bacteriolysin. 



