TRANSPLANTATIONS IN BIRDS 65 



tissue ; or it may represent a rudimentary heterogenous reaction, in which the 

 as yet imperfectly developed organismal differential is able to activate the 

 lymphocytes but is not yet strong enough to act on the polymorphonuclear 

 leucocytes. 



In general, we may conclude from these data that the method used by Blu- 

 menthal is a very useful one if we wish to obtain comparable data of a 

 quantitative nature and that in this respect it surpasses the use of the local 

 reactions. But the latter give an insight into the effect of various types of in- 

 dividuality differentials on different kinds of host cells; it makes possible, 

 furthermore, the differentiation between the effects of the bodyfluids and of 

 the host cells on the transplant. There is, in addition, the possibility that the 

 reactions in the circulating blood are complicated by non-specific or less specific 

 substances which may be present in the transplanted tissues. Thus Blumenthal 

 found that also the introduction of certain non-living protein substances into 

 the subcutaneous tissue may cause an increase of lymphocytes in the blood, 

 similar to that noted after the introduction of living tissues. However, in this 

 case heating the protein substances does not lead to a loss of the general 

 lymphocytic reaction as does the heating of the tissues. Moreover, at least as 

 far as we know at present, the fine shading of the reactions in accordance with 

 the relationship between host and transplant, which is characteristic of the 

 introduction of pieces of living tissue, is lacking in the case of the protein 

 material. These complications are apparently absent in the case of the local 

 reaction. Considering all these facts, it seems that the combined use of these 

 two methods is preferable to the application of either of them alone. 



