640 COLLECTED STUDIES IN IMMUNITY. 



reason to expect haemolysis in Series B to be weaker than in Series 

 A. Under no circumstances could it be stronger. In Series B 

 conditions are such that the " colloid " of these authors would have 

 every opportunity to be absorbed by the weakly prepared blood 

 laden with complement. The result, however, is exactly the reverse, 

 and absolutely contradicts the colloid theory. On the other hand the 

 result it what was to be expected in accordance with our view. 

 The table clearly shows that the ox serum hinders the binding of the 

 horse complement by the weakly prepared ox blood. Proceeding 

 from this fact we arrive at an understanding of the part played by 

 the ox serum in the haemolysis of stongly prepared ox blood by horse 

 serum. We are dealing with rather complicated relations and we 

 have therefore thought it wise to represent these in the attached 

 diagram, figures 3-7. 



Fig. 3 represents the constitution of the immune serum. Ambo- 

 ceptor a is present in weak concentration, while the other, ambo- 

 ceptor 6, is present in strong concentration. 



Fig. 4. pictures our conception of the relations existing when 

 strongly prepared ox blood-cells are digested with horse serum. 

 The immune serum used for preparing the blood contains two 

 types of amboceptor, namely the strongly concentrated amboceptor 

 6, and the weakly concentrated amboceptor a. (See Fig. 3.) The 

 latter is the amboceptor for which the horse complement ca, is 

 dominant. The horse serum, however, contains another substance 

 having complementary properties, c/? and this possesses marked 

 affinity for the complementophile group J3 of amboceptor b. Ambo- 

 ceptor b also possesses a group a which ordinarily does not react 

 with ca. Through the anchoring of component cfi to /? the affinity 

 of this group ca of amboceptor 6 is increased so that now ambo- 

 ceptor 6 lays hold on the effective complement ca with great avidity. 

 Since, however, complement ca is not dominant for amboceptor b, 

 no haemolysis ensues. 



Fig. 5 illustrates the action of the ox serum constituent r. This 

 binds c/?, whereby the increased affinity of group a of amboceptor b 

 fails to occur. This in turn causes ca to unite with a thus giving 

 rise to haemolysis. 



If amboceptor a is absent, i.e., if the ox blood has been weakly 

 prepared, it will be understood that in the digestion with horse serum, 

 amboceptor b binds c/? and through this also ca. The decanted fluid 

 is therefore unable to dissolve strongly prepared blood even when 



