262 Practical Plant Biology. 



they are in reality characters of the embryo enclosed in the 

 seed. 



At first the seeds were tested by sowing the two kinds apart. 

 When mature plants were formed they were automatically self- 

 pollinated. At the same time Mendel guarded by special pre- 

 cautions against other pollen reaching the stigmas. Plants which 

 are thus pollinated with their own pollen are said to be " selfed," 

 while those which receive the pollen from another plant are 

 described as cross-pollinated or crossed. 



When the embryos in successive generations produced by selfing 

 always showed the same allelomorph, whether it was roundness or 

 angularity, it was judged that so far as this character was concerned 

 the peas selected could transmit either allelomorph only. 



Then the experiment was tried of cross-pollinating a plant 

 developed from one of the round peas with the pollen from one 



FIG. 92. Round and angular (or quadrate) peas. 



coming from an angular pea. The reciprocal cross was also made, 

 i.e. the pollen of an angular plant was put on the stigma of a round 

 plant The result was the same from both crosses. Whether the 

 round plant was used as the pollen-parent or the seed-parent, the 

 embryos produced in the pod of the seed-parent were always found 

 to be round. Mendel called the character which thus appeared 

 in the hybrid to the exclusion of the other the dominant character, 

 while that which was not visible he styled the recessive character. 

 In this case he found that roundness is dominant and angularity 

 recessive, no matter which way the cross is made. It may be 

 noted that this indicates that the inheritance of the offspring is 

 equally contributed to by each parent. The first or hybrid gener- 

 ation is called the F 1 generation. 



The flowers of the mature plants developed from these round 

 peas produced by cross-pollination were selfed. Embryos (F 2 

 generation) were developed in the selfed carpels and they were 



