If If if «f «t 9^ •^ 



¥^ «« mm urn »« vv mm 



X Y 



(b) 



Fig. I. Photomicrograph {a) and ideogram (6) of a male cell recovered from the 



bone marrow of a tolerant female parabiont dying of parabiotic disease 33 days 



following the operation (identified by courtesy of Dr. Y. Trujillo, City of Hope 



Medical Center, Duarte, Calif.). 



To face p. 338 



