(n.) A primeval larval form; a double-walled sac from which, according to the hypothesis of Haeckel, man and all other animals, that in the first stages of their individual evolution pass through a two-layered structural stage or gastrula form, must have descended. This idea constitutes the Gastraea theory of Haeckel. See Gastrula.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). Gastraea. Retrieved September 24, 2026, from http://smartdefine.org/gastraea/definitions/2011474 |
| Chicago | Webster's. 2011. "Gastraea" http://smartdefine.org/gastraea/definitions/2011474 (accessed September 24, 2026). |
| Harvard | Webster's 2011, Gastraea, Smart Define, viewed 24 September, 2026, <http://smartdefine.org/gastraea/definitions/2011474>. |
| MLA | Webster's. "Gastraea" 27 May 2011. Web. 24 September 2026. <http://smartdefine.org/gastraea/definitions/2011474> |