Source : Webster's Revised Unabridged Dictionary (1913)

Weismannism \Weis"mann*ism\, n. (Biol.)
   The theories and teachings in regard to heredity propounded
   by the German biologist August Weismann, esp. in regard to
   germ plasm as the basis of heredity and the impossibility of
   transmitting acquired characteristics; -- often called
   {neo-Darwinism}.