CONCERNING ALEXIN ACTION. 



187 



ing the dog serum, and therefore in this case turned first to the com- 

 pletion method. By means of completion of the variously inactivated 

 dog serum with other sera which do not dissolve guinea-pig blood, 

 we hoped to obtain an insight into the circumstances here presented. 

 In this way we were able to convince ourselves that dog serum which 

 had been inactivated by half an hour's heating to 60 C. according to 

 Buchner's procedure, is no longer activated in its hsemolytic action 

 on guinea-pig blood, by the addition of guinea-pig serum. When 

 the dog serum, however, was heated only to 55 C. or even only to 

 50 C. it was always possible to activate such an inactivated serum 

 by means of guinea-pig serum. This was the more readily effected, 

 the lower the inactivating temperature employed. It need hardly 

 be mentioned that in particular cases we always determined whether 

 the serum really was inactive; and this showed that dog serum 

 loses its hsemolytic property for guinea-pig blood completely, even 

 when merely warmed for half an hour to 49 C. We must therefore 

 regard it as a fortunate coincidence that the complement of dog 

 serum is so markedly thermolabile, for only under this condition could 

 it be possible to preserve the amboceptor intact, i.e., capable of react- 

 ing, for that body is but little more stable. Whether the amboceptor 

 heated to 60 has been damaged in its cy tophile or complementophile 

 affinity is still undetermined. One could perhaps also think of a 

 blocking of the complementophile group of the amboceptor due to a 

 binding of the comp ement taking place at the higher temperature. 

 Be this as it may, these experiments certainly show that the power 

 of a dog serum (inactivated at a suitable temperature, e.g., 50 C.) to 

 be activated by guinea-pig serum is lessened by heating the dog serum 

 to 55 C. and destroyed at 60 C. 



Table IV shows such an experiment: 



TABLE IV. 



COMPLETION (WITH GUIXEA-PIG SERUM) OF DOG SERUM INACTIVATED AT 

 DIFFERENT TEMPERATURES. 



