What was Darwin’s hypothesis of pangenesis?

In his work Variation of Animals and Plants Under Domestication, Charles Darwin proposed a "provisional hypothesis" called pangenesis to explain the transmission of traits and the inheritance of acquired characteristics.12

Darwin hypothesized that every part of an organism's body produced invisible, minute particles known as "gemmules". These gemmules were thought to be released into the blood stream and eventually collect in the germ cells. Within the germ cells, these particles would combine with existing units, modifying them to reflect changes that had occurred in the peripheral organs from which they originated. Consequently, the resulting offspring would serve as a "photograph" of the parent at the specific stage when the germ cells were formed.12

This theory was an attempt to explain how variation and acquired traits were passed to the next generation. However, the hypothesis was later dismissed after experiments, such as those conducted by Sir Francis Galton using rabbit blood, failed to provide evidence for the existence of gemmules. Modern biological knowledge has since established that heredity is governed by genes rather than the migration of body-cell particles.23