The question of how to evaluate the relationship between self-fertilization, empty seeds and selfed seeds is discussed. Formulas are worked out, for different situations. The method of making calculations in the various cases is illustrared by examples. The following situations are considered: There is one embryo per ovule. There are two polyzygotic embryos per ovule-genetic death is caused by homozygosity of recessive embryonic lethals - the probability of genetic death is not correlated between embryos of the same ovule. The presence of polyembryony is of considerable importance for the relationship between the factors mentioned. Firstly, the situation where all outbred embryos are viable is considered and later the model is extended to the situation where outbred embryos are allowed to die
