Darwin's Pangenesis: A Theory of Everything?

This chapter briefly discusses Darwin's The Origin of Species and its companion volume The Variation of Animals and Plants under Domestication. It is in the second great book that Darwin took a broad survey of the whole range of variation and heredity, and developed his Pangenesis, an expanded cell theory and a unified genetical theory that would strengthen his theory of evolution and explains the numerous phenomena of life. The essential assumption of Pangenesis is the existence of inherited particles or molecules called gemmules, and their production by cells at each stage of development. He assumed that besides the ordinary cellular division, cells could also "throw off" numerous and minute gemmules, which were capable of self-replication and dormancy, diffusion from cell to cell or circulation through the body, modification by the effects of use and disuse or environmental changes, union with nascent cells, aggregation into buds and germ cells, and transmission from parent to offspring. By his Pangenesis, Darwin not only explained the general phenomena pertaining to inheritance, variation, development and reproduction, but also the inheritance of acquired characters, prepotency, graft hybridization, reversion, regeneration, xenia, telegony, transposition, sex-linked inheritance, the inheritance and non-inheritance of mutilation, and many other facts. Darwin called Pangenesis his "beloved child", and firmly believed that it "will turn out true some day!"