The theory of the continuity of the germ plasm published by August Weismann (1834–1914) in 1886. It proposes that the contents of the reproductive cells (sperms and ova) are passed on unchanged from one generation to the next, unaffected by any changes undergone by the rest of the body. It thus rules out any possibility of the inheritance of acquired characteristics, and has become integral to neo-Darwinian theory. However, Weismann’s dogma is challenged by the finding that epigenetic modifications of chromatin acquired during an individual’s lifetime can be transmitted to their offspring.