No. 630] THE INDIVIDUALITY-DIFFERENTIAL 59 



somes and therefore the corresponding chemical groups 

 present in the cells of the graft. The result should there- 

 fore approach that of homoio-transplantation, which we 

 indeed find to be the case. After transplantation from 

 mother to child the graft finds in the host in many cases 

 the chemical groups it possesses itself, but again the pro- 

 portion of chemical groups in host and graft (corre- 

 sponding to that of the chromosomes) differs here more 

 than in the case of two brothers and these quantitative 

 differences might lead to a greater incompatibility be- 

 tween graft and host than in the case of transplantation 

 from brother to brother. On this assumption we might 

 furthermore expect that in certain rare cases even 

 homoio-differentials should show a similar constitution 

 and might therefore permit a successful transplantation 

 into a not related individual. 



While the somatic tissues require for their normal ' 

 life identity of individuality differentials with which they 

 come into contact, the germ cells on the contrary are 

 normally adapted to contact with homoio-differentials in . 

 the chromosomes and as T. H. Morgan 3 has shown in 

 Ciona secondary mechanisms may even make auto fer- 

 tilization impossible. 



In man, Landsteiner, Moss and others found a peculiar 

 distribution of isoagglutinins into three or four groups, 

 which are apparently independent of the parentage of 

 the individuals concerned. Such a condition seems to be 

 peculiar to man and has not been found in animals 

 (Hecktoen). 4 In certain animals, however, von Dungern 5 

 and Hirschfeld succeeded through immunization to de- 

 monstrate the existence of two kinds of isohemagglutin- 

 ins and of the corresponding antigens and thus of four 

 classes of individuals. As our transplantations show 

 conditions in the tissues cannot be the same as in the red 

 blood corpuscles, if we should judge the constitution of 



8 T. H. Morgan, Biological Bulletin . 190.1, VTIT, 313. 



* L. Hecktoen, J. Infect. Diseases, 1907, IV, 297. 



8 V. Dungern, Munch. Med. Wok., 1910, Vol. 57, p. 293, p. 740. 



