2. White Cap. Additional backcross data show linkage between Wc and T1-9b (31.3% recomb. in 208 plants); Wc and T1-9c (26.0% in 127 plants) and new data show no linkage with T1-10a (149 plants). The breaks in chromosome 1 are: .6 long arm, 6 short arm, and .4(-) long arm respectively. The breaks in chromosome 9 in the first two interchanges are at .5 long arm and .2 long arm respectively. These data indicate chromosome 1 is not the one carrying white cap. A previous test with 9-10a (break at .3 long arm of 9) had shown no positive evidence of linkage from which it was concluded that Wc is in chromosome 1 (1944 news letter). Closer examination of these data shows 35.4%ąS.E.5.1% recombination in one culture, independence in a second, while the combined results do not deviate significantly from 50%. In a backcross linkage test on 190 plants there was no linkage between Wc and P. In the same culture f was segregating 3:1 with no indication of linkage. Wc, therefore, is probably not in chromosome one, but in chromosome 9. If so it is probably in the long arm since a test with waxy showed no linkage (1944 news letter).