1. the region of cytoplasm in an egg cell that is destined to give rise to the germ cells during subsequent embryological development. Compare somatoplasm.

2. the hereditary material that, according to German cytologist August Weismann (1834–1914) in his germ plasm theory (also known as continuity of germ plasm or Weismannism), passes unchanged from generation to generation in the germ cells. It is now identified as DNA.