Darwins theory of inheritance was reffered to pengenesis theory suggesting that small gemmules or pengenes were produced by the animal body, which are deported in the reproductive organ and by blending these gemmules or pengenes new individual is formed. But this theory was rejected by Weismann (1900). He suggested that reproductive cells have the germplasm and they pass traits to the next generation. As the traits of somatoplasm do not transmit to next generation, they are not found in the off springs. This is the basis of present day chromosomal theory of inheritance.