124 



The Journal of Heredity 



GERMINATION OF NORMAL AND DEFECTIVE SEEDS 



Figure 15. When kept in an incubator complete defectives show a germination of only 

 about twelve per cent. The illustration shows some of the defectives which have germmated 

 compared with normal grains from the same ear. Unless transferred to nutrient agar the 

 defectives proceed no farther than the stage shown in the photograph. 



gating for two types of defectives in 

 approximately a nine-seven ratio, show- 

 ing that the two types are genetically 

 distinct and not merely the same char- 

 acter associated with different combi- 

 nations of modifying factors. The 

 two types have also each been crossed 

 with some fifteen other defectives from 

 various sources and appear to be dis- 

 tinct from all of them, although so 

 close! V resembling several of them as 

 to be indistinguishable. 



The third group of defectives we 

 have called germinating seeds. 1 he 

 factor for germinating seeds prevents 

 the mature ovule from going into the 

 resting stage and approximately one- 

 fourth of tbe seeds on a segregating 

 ear l)egin to germinate wbile still at- 



tached to the rachis. Usually the 

 embryo grows only enough to stretch 

 the pericarp and give the seed a swol- 

 len appearance, but in extreme cases 

 the pericarp is burst and a well-defined 

 root and shoot are formed. The char- 

 acter was first ol)served by Jones on 

 a self-pollinated ear of a small New 

 England variety. Canada Flint. It is 

 not at all unusual, especially in New 

 England, to find ears in the field on 

 which part of the seeds have germi- 

 nated. Ordinarily wben this occurs 

 the germinating seeds are confined to 

 a local region of the ear which has 

 not dried out thoroughly. On this 

 ])articular specimen, however. the 

 germinating seeds were scattered at 

 random tlirougbout the ear and oc- 



