Anomalous Endosperm Development in Maize and tlie Problem of Bud Sports. 247 



all independently inherited factors that happened to be in a hetero- 

 zygous condition. 



If these half-and-half seeds were produced by segregation of Men- 

 delian factors at all, the segregation could have included in neither 

 case more than one of the two factors R and S, both of which were 

 heterozygous. In one case the factor S alone must have been concerned 

 in the possible segregation, producing a wholly colored but half starchy 

 and half sugary seed. In the other case only C or R or perhaps both C 

 and R could have been concerned, certainly not S, for the seed was 

 wholly starchy though half white and half purple. 



It seems clear, therefore, that these two anomalous seeds were 

 not produced by Mendelian segregation, if we give that term its usual 

 meaning. "Were they then produced by any sort of segregation? While, 

 so far as I am aware, there are no exact data that bear directly upon 

 this question two possibilities suggest themselves. (1) There may have 

 been vegetative (somatic) segregations (hypothesis III), in which, however, 

 in any one case only one of the heterozygous, genetic factors was con- 

 cerned; or (2) there may have occurred somatic mutations. 



I am aware of no cytological mechanism upon which to base a 

 belief in somatic segregation, and it seems unlikely that such segregation 

 is in any way related to the problem of ontogenetic differentiation. 

 Might it not be possible however — though this is purely speculative — 

 that in some cell division a single chromosome fails to divide and passes 

 entire to one daughter cell? It would be possible to test this notion 

 perhaps, if there could be discovered some other endosperm factor com- 

 monly linked with say S, C or R, that is, another factor carried in the 

 same chromosome with any one of these three factors'). 



It is perhaps noteworthy in this connection that no half-and-half 

 seeds have been reported in maize that was known to be homozygous 

 with respect to endosperm characters. If such phenomena were due to 

 somatic mutations rather than to segregations, why should they not 

 occur in homozygous material? Why should not pure sugar maize, for 

 instance, occasionally produce a seed that is half starchy? Or why 

 should not a white race produce a half-purple seed? Might it not also 

 be expected that a homozygous starchy or colored maize would occasion- 

 ally produce a seed that is half sugary or half colorless? 



') A factor H for horny endosperm (Collins 1) is probably thus linked with C 

 or R — see discussion later in this paper. 



