gemmule
IPA: gˈɛmjʌɫ
noun
- (biology)
- (archaic) Synonym of gemma (“an asexual reproductive structure, as found in animals such as hydra (genus Hydra) and plants such as liverworts (division Marchantiophyta), consisting of a cluster of cells from which a new individual can develop”)
- (specifically, zoology) A small gemma or bud of dormant embryonic cells produced by some freshwater sponges (phylum Porifera) that develops into a new sponge.
- (historical) In the obsolete theory of pangenesis propounded by the English scientist Charles Darwin (1809–1882): a hypothetical particle once thought to be the basis of heredity.
- (botany) Synonym of plumule (“the first bud, or growing point, of a plant embryo, situated above the cotyledons”)
- (neurology) Synonym of dendritic spine (“a small membranous protrusion from the dendrite of a neuron that typically receives input from a single axon at the synapse”)
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Examples of "gemmule" in Sentences
- For our "plumule" we have also "gemmule", and French has both of these too.
- Any part of a gemmule would be an impossible (because a _less_ than possible) quantity.
- We can easily conceive a being so small, that a gemmule would be to it as large as St. Paul's would be to us.
- In this regard, he likened Darwin's gemmule theory to Newton's corpuscular theory of light and the molecular theory of matter.
- The "gemmule" of a Halimeda contained several articulations united, ready to burst their envelope, and become attached to some basis.
- Who cares, after all, that Darwin got his physical theory of inheritance wrong (basing it on a nonexistent entity called the "gemmule")?
- What wonder then that such an excessively complex body should divide and multiply; and what parity is there between such a body and a gemmule?
- It is remarkable that Mr. Darwin brings forward in support of gemmule fission, the observation that "Thuret has seen the zoospore of an alga divide itself, and both halves germinate."
- Darwin's keen analogy of the fertilization of plants by pollen renders development from without conceivable, but as there are no insects to convey gemmules to their destination, each kind of gemmule would have to be exceedingly numerous and easily attracted from amongst an inconceivable number of other gemmules.
- Each gemmule, according to Mr. Darwin, is really the seat of powers, elective affinities, and special tendencies as marked and mysterious as those possessed by the physiological unit of Mr. Spencer, with the single exception that the former has no tendency to build up the whole living, complex organism of which it forms a part.
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