64 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



tion. The conclusion seems therefore justified that the increase after trans- 

 plantations in which host and donor are identical is a non-specific reaction. 



Syngenesiotransplantation of the thyroid in guinea pigs caused an average 

 maximum percentage increase of lymphocytes amounting to 11.7 and the 

 average period of the maximum increase was 12.1 days after transplantation, 

 as compared with the corresponding figures in case of homoiotransplantation 

 of the guinea pig thyroid, which were respectively 16.6 per cent and 7.1 days. 

 The increase in the lymphocytes after syngenesiotransplantation was therefore 

 less than after homoiotransplantation and it appears later, indicating a milder 

 reaction in the former, a fact which harmonizes with the decreased disharmony 

 of the individuality differentials between nearly related individuals as com- 

 pared to not nearly related, homoiogenous individuals. 



The conclusion that relationship between the individuality differentials of 

 host and donor is the decisive factor in the changes in the distribution of white 

 blood cells following various types of transplantation agrees also with the 

 results obtained in mice. After transplantation of tissues to a different strain, 

 the average lymphocytic increase was 17.7 per cent, and after transplantation 

 within the strain it was 12.1 per cent. However, after transplantation within 

 strain A, the most closely inbred strain, the increase in the lymphocytes was 

 only 10 per cent and the maximum increase appeared somewhat later, on the 

 average, after 13.6 days. These transplantations correspond therefore to the 

 syngenesiotransplantations in the guinea pig. The response of strain A mice to 

 heterogenous transplants from the rat was similar to that seen in other types of 

 heterogenous transplants ; the average increase in polymorphonuclear leuco- 

 cytes was 18.7 per cent ; it set in between the 2nd and 4th day and, as usual, was 

 followed by a secondary rise in lymphocytes. There was not only a relative in- 

 crease in the lymphocytes or leucocytes in the various types of transplantations, 

 but also an absolute increase, which was even more striking than the relative 

 increase. In the guinea pig the absolute increase in the number of lympho- 

 cytes amounted to about 78 per cent and in the rat to about 54 per cent, while 

 the average increase in polymorphonuclear leucocytes reached about 110 per 

 cent. 



This method of analyzing the individuality differentials lent itself well to a 

 comparison between the individuality differentials in adult and in embryonal 

 tissues. It was found that tissues obtained from fully developed embryos near 

 the time of labor behaved after homoiogenous and heterogenous transplanta- 

 tion in the same way as the corresponding adult tissues. On the other hand, 

 very young embryonic tissues removed from an animal at about the conclusion 

 of the first third of pregnancy behaved differently ; here, after heterogenous, 

 as well as after homoiogenous transplantation, a lymphocytic response similar 

 to that noted after homoiogenous transplantation was observed, while an in- 

 crease in the number of polymorphonuclear leucocytes in the host was lacking 

 under these conditions. This indicates that the typical heterogenous organismal 

 differentials had not yet developed in these cases. But the lymphocytic reac- 

 tion may correspond to the increase in lymphocytes in the blood noted after 

 transplantation of various dead protein substances into the subcutaneous 



