GENETIC CONTROL OF CELL INTEGRATION 



343 



FIGURE 11.19. Photographs of corn kernels demonstrating the effect of dosage of 

 Ac upon the time of occurrence of Ds-induced chromosomal breaks. 



(o) and (b). One Ac is present and the breaks at Ds occur early in development 

 giving rise to large sectors. 



(c). The pattern produced v/hen two doses of Ac are present indicates the late 

 time of occurrence of Ds breaks. 



(d). When three doses of Ac are present, the Ds-induced breaks occur so late 

 that only a few colored specks can be seen. In all plants used in these crosses, the 

 genotype of the female parent was C bz/C bz and the male was / Bz Ds with Ds 

 located between 62 and the centromere. / is a dominant inhibitor of pigmentation, 

 allelic to C (from McCiintock, 1951, C. S. H. Symp. Quanf. Biol., 16:13). 



