Weismann barrier

The Weismann barrier, proposed by August Weismann, is the strict distinction between the "immortal" germ cell lineages producing gametes and "disposable" somatic cells in animals (but not plants), in contrast to Charles Darwin's proposed pangenesis mechanism for inheritance.

[8] It remains important, but has however required qualification in the light of modern understanding of horizontal gene transfer and some other genetic and histological developments.

Rather Medvedev thought that known features of the biochemistry and genetics of sexual reproduction indicated the presence of unique information maintenance and restoration processes at the different stages of gametogenesis.

[11] In plants, genetic changes in somatic lines can and do result in genetic changes in the germ lines, because the germ cells are produced by somatic cell lineages (vegetative meristems), which may be old enough (many years) to have accumulated multiple mutations since seed germination, some of them subject to natural selection.

[12] It is noteworthy in this context that, generally speaking, adult, reproducing plants tend to produce many more offspring in number than animal organisms.