246 Liners on. 



no less trustworthj- than cytological evidence. We may inquire, then, 

 what help is given by the genetic evidence in attacking the problem 

 of the mode of vegetative segregation? If there is any such thing as 

 vegetative segregation, can it be typical Mendelian segregation? 



Let us first consider in this connection the two cases of anoma- 

 lous endosperm development in maize seeds reported earlier in this 

 paper. Recall first that each polar nucleus had a genetic constitution 

 represented by the formula CrPs and that the second male nucleus was 

 cRPS. The fused polar nuclei must then have been CCrrPPss and 

 the "fertilized" endosperm nucleus CCcRrrPPPSss. If now there occur 

 "Mendelian" segregation of these factors in the division of such a cell 

 or of any of its descendants, what result will that segregation produce? 

 As a matter of fact there is nothing upon which to base a guess as to 

 how Mendelian factors might segregate when in the triplex condition 

 evident here. 



Of course there is the cytological evidence of what occurs at the 

 reduction division in triploid Fi plants of hybrids between diploid and 

 tetraploid forms of Oenothera (Gates (13, 14); Geerts (15)), and the 

 chromosome behavior of Drosera hybrids (Rosenberg (16)) also na- 

 turally comes to miud. It seems unlikely, however, that these cases 

 have any bearing upon the problem in hand. There is no evidence that 

 anything like a reduction of chromosomes occurs in the formation of 

 half-and-half endosperms or in the origin of other bud sports. 



Fortunately, for our immediate problem, it is not necessary to 

 know just how triplex Mendelian factors might behave in segregation. 

 It is perfectly obvious, even without that information, that, if in a cell 

 CCcRrrPPPSss a division results in any segregation such that the three 

 factors C, R and S go to one daughter cell, neither R nor S can go 

 to the other daughter cell. Perhaps the second C factor and two P 

 factors might go with C, R, and S or perhaps C and one P might go 

 to the other daughter cell with c, r and s or c, rr and ss etc., but 

 this has no bearing ui)on our problem. If one daughter cell has C, R 

 and S, it has the Mendelian factors necessary for the pioduction of 

 aleurone color and starchiness. And if the other daughter cell lacks 

 both R and S, it could develop neither aleurone color nor starchiness. 

 Since the two maize seeds described earlier in this paper were starchy 

 and colored on one side but were not both sugary and colorless on the 

 other side, they could not have been produced by any segregation of 

 factors that could be termed Mendelian in the sense that it involved 



