IMMUNOGENETICS OF TUMOURS IN CHIMERAS 



171 



another experimental system in which an induced homotrans- 

 plantability of strain-specific tumours was achieved. The 

 "inducing" environment, in their case, was embryos of foreign 

 genetic constitution, or "foreign" newborn which had been made 



Fig. I. The establishment of homotransplantable SBLx subHnes, from SBLi, 

 grafted on isologous C3H chimeras. 



tolerant to the isoantigens of the tumour. A comparison of the 

 genetic properties of the two systems points to two possible 

 factors which might influence such changes: (i) a low immune 

 response of the inducing environment; and (2) the prolonged 

 growth of the tumour in a foreign antigenic background. 



