what is pangenesis theory?
According to this theory  each part of the parent's body emitted tiny particles called gemmules, which migrated through the body to contribute to that parent's gametes, their eggs or sperms.
Blending inheritance
Pangenesis was Darwin's attempt to provide such a mechanism of inheritance. The idea was that each part of the parent's body emitted tiny particles called gemmules, which migrated through the body to contribute to that parent's gametes, their eggs or sperms. 
why is incomplete dominance not evidence for the blending theory of inheritance UNANSWERABLE
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Blending inheritance [SEP] Darwin's pangenesis
All of this demanded a reliable mechanism of inheritance. Pangenesis was Darwin's attempt to provide such a mechanism of inheritance. The idea was that each part of the parent's body emitted tiny particles called gemmules, which migrated through the body to contribute to that parent's gametes, their eggs or sperms. The theory had an intuitive appeal, as characteristics of all parts of the body, such as shape of nose, width of shoulders and length of legs are inherited from both the father and the mother. However, it had some serious weaknesses. Firstly, many characteristics can change during an individual's lifetime, and are affected by the environment: blacksmiths can develop strong arm muscles during their work, so the gemmules from these muscles ought to carry this acquired characteristic.