JOINT ACTION OF SEVERAL AMBOCEPTORS. 641 



inactiveox serum is present. (See Fig. 6 and also Table 12, A, of 

 the text.) 



Furthermore, if the weakly prepared blood, which then has only 

 bound amboceptor 6, is digested with the mixture of horse serum 

 and inactive ox serum, no haemolysis occurs because the effective 

 amboceptor a is absent. Since, however, the ox component r binds 

 c/?, ca is left free. In this case if the decanted fluid is poured over 

 strongly prepared ox blood, it will be found that haemolysis occurs 

 without any further addition. (See Fig. 7, and experiment Table 

 12, B.) 



Naturally, in addition to the factors described above, the effects 

 of mass action must be considered. Thus if a small quantity of ox 

 serum is made to react with a great excess of amboceptor b, it is 

 evident that the reaction between 6 and c can still take place. It will, 

 however,- be slower and less complete than when the ox serum is 

 entirely absent. If then amboceptor a is present at the same time 

 it will be understood that a portion of c will still find opportunity to 

 combine with it so that hsemoylsis occurs. But when amboceptor a 

 is absent, that is when the ox blood is weakly prepared, c will still 

 be able to combine with amboceptor b and the decanted fluid will 

 have lost its hsemolytic power. This explains a point in Table 12. 

 In the control which consisted of simple mixtures of strongly pre- 

 pared ox blood, 0.35 cc. horse serum, and decreasing amounts of 

 inactive ox serum, it was found that 0.1 cc. of the inactive ox serum 

 still produced complete ha?molysis. In Table 12, B, on the other 

 hand, weakly prepared ox blood deprived a mixture of 0.1 cc. inactive 

 ox serum plus 0.35 cc. horse serum of its hsemolytic power. 



Contrariwise we should expect to find the effective horse com- 

 plement kept intact after digestion with weakly prepared ox blood 

 provided the excess of inactive ox serum is allowed to act at the same 

 time. This is well shown in the following experiment: 



Two series of tubes are prepared: 



Series A. Each tube contains 0.5 cc. weakly prepared 10% ox blood plus 

 0.5 cc. salt solution plus decreasing amounts of active horse serum. 1 



Series B. Each tube contains 0.5 cc. weakly prepared 10% ox blood plus 

 0.5 cc. inactive ox serum plus decreasing amounts active horse serum. 3 



The mixtures are kept for It hours at 37 and then centrifuged. The slight 

 amount of htemolysis observable in series B is shown in Table XIII. 



1 Horse serum plus salt solution previously kept at 37 for one hour. 



2 Horse serum plus ox serum previously kept at 37 for one hour. 



