JOINT ACTION OF AMBOCEPTORS IN H^MOLYSIS. 605 



combinations, we must furthermore conclude that the absence 

 of antilytic action of native serum is only apparent. Haemolysis 

 of the sheep blood-cells by the immune serum is inhibited, but in 

 place of this the normal amboceptors of rabbit serum come into 

 play and effect haemolysis with the aid of the complement of guinea- 

 pig serum. This, of course, affords a natural explanation for the 

 specificity of the phenomenon. The rabbit serum which was treated 

 with sheep blood-cells has lost the amboceptors for sheep blood, 

 but still contains those for pig blood. Hence it inhibits only the 

 haemolysis of sheep blood by immune serum. When the serum 

 is treated with pig blood, the behavior, of course, is just the reverse 

 of this. 



This explanation of the specificity harmonizes very well with 

 the view that the inhibiting substances are anticomplements. It 

 is only necessary to assume that the anticomplements act specifically 

 in the sense that under suitable conditions only the immune and 

 not the normal amboceptors are prevented from combining with 

 the complement. It might be assumed, for example, that the 

 activation of normal and immune amboceptors is effected by dif- 

 ferent complements. It seems simpler, however, to assume that 

 the complementophile group of the normal amboceptors has a 

 greater affinity than that of the immune amboceptor. At first 

 sight this may appear remarkable, but it is not really so. It is 

 true that one can usually regard the immune amboceptors as having 

 the stronger affinity, but this greater affinity applies only to the 

 cytophile group, i.e., the group whose occupation really gave rise 

 to the immunity reaction. So far as the normal amboceptors are 

 concerned, there is another reason for believing that the comple- 

 mentophile apparatus possesses a greater affinity. Anticomple- 

 ments, as Ehrlich and Morgenroth 1 have already shown, are noth- 

 ing more than amboceptors which have reached the blood stream. 

 According to this view, artificially produced anticomplements 

 are amboceptors which differ from the amboceptors produced in 

 response to cells injections, only in the fact that their thrusting- 

 off is due to the occupation of their complementophile group. Orig- 

 inating in this way, a natural selection of complementophile groups 

 with the greatest affinity, of course, occurs and this subsequently 

 shows itself in the increased affinity for the anticomplements. 



1 Ehrlich and Morgenroth. Fifth Communication on Haemolysins. See 

 page 71 of this volume. 



