What is "pangenesis"

Pangenesis \Pan*gen"e*sis\, n. [Pan- + genesis.] (Biol.) An hypothesis advanced by Darwin in explanation of heredity.

Note: The theory rests on the assumption, that the whole organization, in the sense of every separate atom or unit, reproduces itself, the cells throwing off minute granules called gemmules, which circulate freely throughout the system and multiply by subdivision. These gemmules collect in the reproductive organs and products, or in buds, so that the egg or bud contains gemmules from all parts of the parent or parents, which in development give rise to cells in the offspring similar to those from which they were given off in the parent. The hypothesis also assumes that these gemmules need not in all cases develop into cells, but may lie dormant, and be transmitted from generation to generation without producing a noticeable effect until a case of atavism occurs. This is an ingenious hypothesis, but now known to be wrong. Although now, a hundred years later, we know that all transmitted genetic information (other than that in plasmids) is contained in the genome of a single cell, scientists are still only beginning to understand the development process.

n. A mechanism for heredity proposed by http://en.wikipedia.org/wiki/Charles%20Darwin long before the true mechanism was discovered, according to which the cells of the body shed "gemmules" which collect in the reproductive organs prior to fertilization.

Pangenesis was Charles Darwin's hypothetical mechanism for heredity. He presented this 'provisional hypothesis' in his 1868 work The Variation of Animals and Plants under Domestication and felt that it brought 'together a multitude of facts which are at present left disconnected by any efficient cause'. The etymology of the word comes from the Greek words pan (a prefix meaning "whole", "encompassing") and genesis ("birth") or genos ("origin"). The hypothesis was eventually replaced by Mendel's laws of inheritance.

The pangenesis theory, similar to Hippocrates's views on the topic, imply that the whole of parental organisms participate in heredity (thus the prefix pan) while adapting to cell theory. Much of Darwin's model was speculatively based on inheritance of tiny heredity particles he called gemmules that could be transmitted from parent to offspring. Darwin emphasized that only cells could regenerate new tissues or generate new organisms. He posited that atomic sized gemmules formed by cells would diffuse and aggregate in the reproductive organs.