186 



COLLECTED STUDIES IN IMMUNITY. 



peared to be insurmountable. Despite numerous variations in the 

 conditions of the experiment we did not succeed with appropriate 

 procedures in effecting a separation by means of the "cold method. " 

 The fluids decanted from the mixture of guinea-pig blood-cells and 

 active dog serum manifested the same behavior, so far as hamolytic 

 action was concerned, on normal guinea-pig blood and such as had 

 previously been treated with inactive dog blood; and yet they showed 

 slight differences so that we did not feel justified in drawing any 

 conclusion. However, we soon became convinced that a separation of 

 two substances causing haBmolysis had nevertheless been effected by 

 the absorption in the cold. We allowed the fluid decanted from the 

 guinea-pig blood-cells previously treated with active dog serum, which 

 fluid only slightly dissolved native guinea-pig blood, to act on guinea- 

 pig blood sediments, which also had previously been mixed with 

 active dog serum. We were then able to determine that these sedi- 

 ments were strongly, in appropriate quantities completely, dissolved 

 by the decanted fluid, although when mixed merely with salt solution 

 and placed into an incubator they did not dissolve at all, or dissolved 

 only in traces. An experiment of this kind is shown in Table III. 



TABLE III. 

 ABSORPTION OF DOG SERUM BY GUINEA-PIG BLOOD AT C. 



Hence by means of the absorption with guinea-pig blood in the cold, 

 the active dog serum was separated into two components each of which 

 by itself was incapable of effecting solution. One of these became attached 

 to the red blood-cells, the other remained in the fluid. The former there- 

 fore corresponded in its behavior to the amboceptor, and it was only 

 a coincidence that dog serum inactivated by heating to 60 C. was unable 

 also to assume that role. We hoped to discover more about the nature 

 of this curious behavior by employing a different method of inactivat- 



