Anomalous Endosperm Development in Maize and the Problem of Bud Sports. 243 



were crossed with a white seeded aleuroiie tester ccRRPP'), some «rave 

 wholly white ears, some ears with white and purple seeds in approxi- 

 mately equal numbers, and some wholly purple ears. The latter plants 

 must have had homozygous C and lacked R. They must also have had 

 homozygous P, since both parents of the original cross had that factor. 

 Their formula, therefore, was CCrrPP. It is with one of these plants 

 that we are now concerned. 



The F2 seeds exliibitiug the 9 — 7 ratio, noted above, were all 

 sugary (wrinkled), as were the parental and Fi seeds. The aleurone 

 tester used was homozygous starchy. If S be a factor that changes 

 the sugary to the starchy condition, the white-seeded aleurone tester 

 (figure 1) noted above was ccRRPPSS and the white seeded plants 

 with which it was crossed (figure 3) to produce wholly purple-seeded 

 ears were CCrrPPss. The purple seeds thus produced (figure 2) were 

 of course CcRrPPSs. All but two of these were wholly starchy and 

 evenly colored (except for a slight mottling often seen in seeds hetero- 

 zygous for aleurone color). The two exceptional seeds occurred on the 

 same ear. One of them (figure 4) was wholly starchy, but somewhat 

 over one half of it was purple and the other half white. The other 

 one (figure 5) was dark purple throughout, but one part (approximately 

 thi'ee-fifths) was wrinkled (sugary) and the other part smooth (starch}')- 



The bearing of these results upon the three hypotheses noted 

 earlier in this paper is clear. Just as in East's cases, the fact that 

 aleurone color was produced in the half-and-half seeds rules out hypo- 

 thesis I, independent development of the second male nucleus. The fact 

 that one of these seeds was starchy throughout and that the other was 

 purple throughout likewise rules out hypothesis 11 — at least for these 

 cases. If one polar nucleus had developed independently to form a 

 part of the endosperm, that part must have been both colorless and 

 sugary, instead of colorless and starchy or colored and sugary as 

 actually happened. There is left for these cases, then (until someone 



') Of course it cannot be told whether a given type is ccRR or CCrr. One or 

 the other of any two strains of colorless maize, which when inter-crossed produce colored 

 seeds, must be arbitrarily designated by one or the other of these formulae. After tliat 

 the formulae of other strains can be determined by crossing. Since I have never 

 crossed any of my strains with any of Easts, my CCrr is just as likely to be his 

 ccRR as his CCrr. My factor P is of course the same as East's, since this factor can 

 be identified without difficulty. 



16* 



