Source : Webster's Revised Unabridged Dictionary (1913)

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.