22 DISCUSSION 



of tumour, are wholly dissociable except genetically; they are not alike 

 in their sensitivity to temperature, to formalin, to ordinary forms of 

 lysis, or to high-pitched audible, not supersonic, sound. Generalization 

 here may be very misleading. 



Medawar: I entirely agree, one must always keep in mind the parti- 

 cular strain combination one is dealing with. One cannot generalize, 

 for example, from H-2 to non-H-2 differences in mice. 



Barrett: In the mouse and some other species we emphasize the 

 importance of these loci which seem to control the generation of 

 haemagglutinins. I am not too familiar with the Hterature on this but I 

 believe that plastic surgeons have found that blood grouping in the 

 human being is not informative as to the outcome of subsequent grafts. 

 I would like to hear the views of members of the symposium on this. 



Medawar: All that has been proved about human blood groups and 

 their relations with grafts is that blood-group compatibility is not 

 sufficient for the success of grafts; but it may well be necessary. 



Brent: Having recently had an opportunity of reading the literature 

 on kidney transplantation in human beings, it struck me very forcibly 

 that in the four cases in which there has been moderately successful 

 transplantation of kidneys with the aid of irradiation there has also been 

 pretty good correlation between the red cell antigens of the donor and 

 recipient. This rather suggests that matching of red cell antigens can be 

 a rough guide as to the chances of success in organ transplantations. 



Kandutsch: I am not a serologist, but it seems to me that one cannot 

 obtain any absolute measure of the purity of an antigenic preparation 

 from the absorption of antibodies. Dr. Stimpfling has done this test 

 with our preparations but I have not thought that it was possible to 

 judge purity on this basis. 



I would Hke to hear more about the inactivating effect of Triton on 

 your preparation. We have used this extraction with Triton for 

 several years now, and we get very little inactivation. I wonder if you 

 could tell me in more detail the pH and other conditions under which 

 you carried out this inactivation. 



Medawar: The difficulty about our in vivo experiments with deoxy- 

 cholate and Triton is that unfortunately we have to inject the whole 

 preparation, detergent and all, and the antigen is thereupon promptly 

 precipitated. The pH was neutral and the material was injected after it 



