1. The hereditary determinants are of a particulate nature. These determinants are called genes.
2. Each parent has a two alleles in each cell for each trait studied. The F1 from a cross of two pure lines contains one allele for the dominant phenotype and one for the recessive phenotype. These two alleles comprise the allelic pair.
3. One member of the allelic pair segregates into a gamete, thus each gamete only carries one member of the gene pair.
4. Gametes unite at random and irrespective of the other allele involved.
