The theory of Augustus Weismann (1834-1914) that the cells destined to become reproductive cells are segregated very early in development and are thus untouched by influences from the environment or from anywhere else in the body. They are transmitted unchanged from generation to generation (and thus are ‘immortal’) and have no role in development, but do undergo differentiation themselves. The theory stood in marked opposition to the form of Lamarckism that existed in the 19th century (termed ‘neo-Lamarckism‚aa), and in which heredity was considered to be like learning and memory (i.e., characteristics acquired in one generation are passed on to, and retained in, the next one)
. See Central dogma of molecular biology, Chromosome, Germ plasm, Lamarckism, Mendelian genetics