644 COLLECTED STUDIES IN IMMUNITY. 



EXPLANATION OF THE FIGURES ON THE PLATE. 



FIGS. 1 and 2 illustrate the haemolysis of guinea-pig blood by the combined 



action of active horse serum and inactive ox serum. 

 2 = guinea-pig blood-cell; ar = amboceptor of ox serum; ap = amboceptor of 



horse serum; c = complement of horse serum. 



FIG. 1 represents the conditions obtaining when blood, horse serum, and ox 

 serum are mixed simultaneously. The ox amboceptor (ar) combines 

 with the horse complement (c) and thus brings about haemolysis. 

 FIG. 2. The guinea-pig blood is first digested with horse serum (ap + c). The 

 blood-cell absorbs the horse amboceptor (ap) and this in turn anchors horse 

 complement (c) . The ox amboceptor (ar) subsequently added does not find 

 any horse complement (c) at its disposal, and haemolysis therefore does not 

 occur. 

 FIGS. 3-7 illustrate the haemolysis of ox blood laden with amboceptor, by the 



combined action of active horse serum and inactive ox serum. 



z=ox blood-cell; a and b = partial amboceptors of the immune sera (a weakly 



concentrated, and b strongly concentrated) ; a and /? = complementophile 



groups; ca = the horse complement dominant for amboceptor a; c/? = the 



second complement-like constituent of horse serum. This is dominant 



neither for a nor for b; its union, however, with amboceptor b makes 



the complementophile group a of amboceptor 6 capable of reacting. 



= active constituent of ox serum (anticomplement amboceptor?) which 



binds c/9. 



FIG. 3. This shows the constitution of the immune serum. Amboceptor a is 



present in weak concentration, amboceptor 6 in strong concentration. 

 FIGS. 4 and 5 illustrate the mechanism of the haemolysis of strongly prepared ox 



blood by horse serum and inactive ox serum. 



FIG. 4. Strongly prepared ox blood is digested with horse serum. Constituent 

 c/? of the horse serum is bound by amboceptor b, and this union causes 

 horse complement ca to combnie with amboceptor b. Since ca, however, 

 is dominant only for a and not for b, no haemolysis takes place. 

 FIG. 5. Strongly prepared ox blood is digested with a mixture of active horse 

 serum and inactive ox serum. Ox serum constituent r binds component c/3 

 of the horse serum, and c/? is thus prevented from uniting with amboceptor b. 

 Since the latter, however, does not by itself react with horse complement ca, 

 ca is bound by amboceptor a and haemolysis is brought about. 

 FIGS. 6 and 7 illustrate the conditions obtaining when ox blood is prepared with 

 a slight amount of immune serum, and when, therefore, only amboceptor 6 

 has been bound by the blood-cells. 



FIG. 6. Weakly prepared ox blood is digested with horse serum, e/? is bound 

 by b, and this union causes ca to combine with b. No haemolysis occurs. 

 On centrifuging, no horse complement is found in the decanted fluids. 

 FIG. 7. Weakly prepared ox blood is digested with a mixture of horse serum 

 and inactive ox serum. Component r of the ox serum combines with c/?. 

 As a result of this ca is not bound by b, and remains free. On centrifuging, 

 the decanted fluid contains the horse complement. 



