1. Paired red and dark purple mosaic areas in light purple seeds, heterozygous for Pr pr pr, rarely show growth changes. In some of these cases the red area grows out beyond the normal cells, sometimes the dark area. In the few cases that have been examined so far no growth changes accompany the exchange of both Pr and Bt. Since Bt is close to the centromere, presumably, paired changes that include Pr and Bt involve an exchange of almost the entire right arm of chromosome 5. If the alteration in growth were due to a loss or accumulation of specific growth regulating genes or to a general chromosome unbalance it would be expected that all of the paired changes involving both Bt and Pr would be altered. Since they are not, this is a strong indication that growth changes result from breaks and reattachments at critical places in the chromosomes.