यौन और असभ्य पीढ़ियों का विकल्प

Noun:

जन्म के बीच एकांतरण, पीढीएकांतरण,

metagenesis's Usage Examples:

Brooks, " The LifeHistory of the Hydromedusae: a discussion of the Origin of the Medusae, and of the significance of Metagenesis," Mem.

It will be seen elsewhere, however, that whatever view may be held as to the origin of metagenesis in Hydromedusae, in the case of Scyphomedusae (q.v.) no other view is possible than that the alternation of generations is the direct result of larval proliferation.

Brooks [4], who adduces strong evidence for a contrary view, that is to say, for regarding the direct type of development seen in Trachylinae as more primitive, and the metagenesis seen in Leptolinae as a secondary complication introduced into the life-cycle by the acquisition of larval budding.

A similar origin for metagenesis has been discussed under the Hydromedusae (q.v.).

The development from the egg may be direct, or may take place with an alternation of generations (metagenesis), in which a non-sexual individual, the so-called scyphistoma or scyphopolyp, produces by budding the sexual medusae.

It is quite possible that some of these medusae will be found to be truly hypogenetic, that is to say, with a life-cycle secondarily simplified by suppression of metagenesis.

In Trachylinae also the beginnings of a similar metagenesis can be found.

Hence the alternation is of the type termed metagenesis.

They typically present two structural forms, the non-sexual hydroid and the sexual medusoid; in such a case there is an alternation of generations (metagenesis), the hydroid giving rise to the medusoid by a sexual gemmation, the medusoid bearing sexual cells which develop into a hydroid.

- Hydro- medusae with alternation of generations (metagenesis)in which a non-sexual polypgeneration (trophosome) produces by budding a sexual medusa-generation (gonosome).

metagenesis's Meaning':

alternation of sexual and asexual generations