HERITABLE CHARACTERS OF MAIZE 



XV — Germless Seeds' 



^r. Demerec 



Station for E.vpcriniciital livolutiou. Cold S [^vnuj Harbor, N. Y 



IN the winter of 19"2"3 a peculiarity 

 was noted on ths germinal side of 

 several seeds taken from a selfed 

 ear. Closer observation revealed the 

 fact that these seeds lacked the germ. 

 The ratio of normal and germless 

 seeds taken from the same ear indi- 

 cated that the germless condition might 

 be an inherited character. Further ob- 

 servations established this fact and 

 gave the results presented below. 



Description of Germless Seeds 



As far as size and shape are con- 

 cerned the germless seeds are normal 

 or practically normal. When examined 

 from the side opposite the germ in 

 most cases they cannot be distinguished 

 from normal seeds. When viewed 

 from the germinal side the difference 

 between the normal and germless seeds 

 can be readily detected. The germinal 

 area of a germless seed is without a 

 sharj) margin. It is more sunken than 

 in a normal seed and is covered with 

 wrinkled pericarp, which looks trans- 

 lucent because of air cavities below. 

 If a germless seed is split vertically a 

 cavity is found in the place where the 

 germ is normally located. The differ- 

 ence between the normal and germless 

 seeds can be seen from Figure 3. 



When a seed with sugary endosperm 

 is germless. the germinal area is still 

 less distinct and in many cases the 

 germinal and opposite sides can hardly 

 be distinguished. 



From the observed ratios it can be 

 concluded that the germless condition 

 is a result of the union of two gametes 

 both of which are carrying necessary 

 recessive factors. The fertilization is 

 apparently accomplished and the de- 



'Paper No. Ill, Department of Plant Bre 



veloi)ment of the endosperm proceeds 

 normally, but the development of the 

 embrvo is stopped in some early stage 

 of its growth. Up to this time only 

 mature seeds have been examined. In 

 some of them only traces of an em- 

 bryo could be detected ; in others no 

 signs of a developing embryo could 

 be seen. 



Inheritance of Germless Seeds 



No special crosses were made for the 

 study of the inheritance of germless 

 seed. It was possible, however, to 

 trace the behavior of the character 

 through several generations, because it 

 was found in several families grown 

 for the genetical study of other char- 

 acters. 



A G3 :1 Ratio — Three plants had 

 been pollinated with the pollen from a 

 Golden Bantam sweet corn plant, which 

 was apparently heterozygous for germ- 

 less. Part of the first generation ears 

 grown from these crosses had all seeds 

 normal, and the other part segregated 

 into normal and germless. with the 

 totals given in Table I. 



A plant from family 311 was 

 crossed with another plant from a dif- 

 ferent family which did not throw 

 germless seed. Part of the second 

 generation ears were normal and the 

 other part segregated as shown in 

 Table II. 



The occurrence of 63:1, 15:1 and 

 3 :1 ratios in the progenies of the 

 crosses made by the pollen from a sin- 

 gle plant and its progeny, indicates 

 that in this case the homozygous con- 

 dition of at least three genes was 

 necessary for the expression of the 

 germless character. . 



eding, Cornell University, Ithaca, New York. 



297 



