Definition of "gemmule"

(biology)

1. (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”)  quotations

   Quotations

   • A very similar mode of growth and propagation is found among the compound Polypes, whose gemmules, like those of the Medusæ, are at first free, and moved by cilia; afterwards attached, and budding forth with a plant-like body.

     1849, W[illiam] H[enry] Harvey, “The Microscopic Wonders of the Sea”, in The Sea-side Book; being an Introduction to the Natural History of the British Coasts, London: John Van Voorst, […], page 198

   • Accidental hematozoa may be found, […] in the vessels of man and other animals; these are foreign to the blood, and do not circulate with it. The hydatid, acephalocystis endogena, detaches its gemmules from its inner surface; one thus inclosing the other in a series, like pill-boxes. It is found in the liver, kidney, womb, etc.

     1855, Samuel Henry Dickson, “Exciting Causes of Disease. [Parasites—Animal and Vegetable.]”, in Elements of Medicine: A Compendious View of Pathology and Therapeutics; or The History and Treatment of Diseases, Philadelphia, Pa.: Blanchard and Lea, section II (Etiology), page 108

   • They [spores and tetraspores] may rather be considered, the one a true spore, supposed to be fertilized by means of an antheridium; the other, a mere gemmule, or bud of the simplest possible structure, which is cast off by the parent plant, and carries with it sufficient vitality to become the nucleus of a fresh individual.

     1867, Samuel Octavus Gray, “The Position of Sea-weeds in the Vegetable Kingdom; Their Structure, etc.”, in British Sea-weeds: An Introduction of the Study of the Marine Algæ of Great Britain, Ireland, and the Channel Islands, London: L[ovell] Reeve & Co., […], page 12

   • The gemmules of the Marchantia [a genus of liverworts] are little disc-shaped masses of cells composed of two or more layers.

     1867, Herbert Spencer, “Differentiations among the Outer Tissues of Plants”, in The Principles of Biology (A System of Synthetic Philosophy; III), volume II, London, Edinburgh: Williams and Norgate, […], § 272, page 235

   • The ova [of the brown hydra, Hydra oligactis, formerly Hydra fusca] covered with a horny substance possess a great power of resistance to the cold, thus preserving their vitality until the return of conditions favorable for their existence, when development begins to take place. This proceeds up to a certain point, the covering of the ovum bursting, liberates the embryo, which becomes ciliated, and for some time swims freely in the water; in this condition it is known as a "gemmule."

     1867 April, J. Josselyn Ranson, “General Meeting. [Hydræ, or Freshwater Polypes.]”, in W[illia]m Lant Carpenter, editor, Proceedings of the Bristol Naturalists’ Society, (Established 1862,) for the Year 1867, volume II, number 4, Bristol: […] [F]or the [Bristol Naturalists’] Society by G. Morris, […], page 40

   1. (specifically, zoology) A small gemma or bud of dormant embryonic cells produced by some freshwater sponges (phylum Porifera) that develops into a new sponge.  quotations

      Quotations

      • Sponges are propagated by gemmules, which originate in the organic mucus, and are carried out of the body by the effluent currents just described. In some sponges these gemmules are ciliated and locomotive when mature; but it seems probable that the majority of the species produce only unciliated gelatinous grains, which are nevertheless endowed with a very active motility, like the ultimate particles of even inorganic matter.

        1860, G. J., J. Y. J., “ZOOPHYTES”, in The Encyclopædia Britannica, or Dictionary of Arts, Sciences, and General Literature. […], 8th edition, volume XXI, Edinburgh: Adam and Charles Black, part VI (Sponges), page 1008, column 2

      • The increase in size of the gemmule takes place by means of cell growth and division, and by the fusion of neighboring small gemmules.

        1891 July–December, Henry V[an Peters] Wilson, “Notes on the Development of Some Sponges”, in Journal of the Elisha Mitchell Scientific Society, volume VIII, part 2, Raleigh, N.C.: E. M. Ezzell, […], published 1892, page 97

      • The green fresh-water sponge dies away in autumn, all but little pinhead clusters of cells called gemmules, which eventually float away from the dead skeleton and start new sponges in the spring.

        1931, J[ohn] Arthur Thomson, Patrick Geddes, “Ecological”, in Life: Outlines of General Biology, volume 1, London: Williams & Norgate, page 54

      • All fresh-water and some marine sponges reproduce asexually by means of gemmules; these embryos are formed simply by assembly of a few amoebocyte cells. Reproduction is also accomplished sexually by the union of sperm and egg cells.

        1964 March, John F. Storr, “Introduction”, in Ecology of the Gulf of Mexico Commercial Sponges and Its Relation to the Fishery […] (United States Fish and Wildlife Service Special Scientific Report—Fisheries; no. 466), Washington, D.C.: Bureau of Commercial Fisheries, Fish and Wildlife Service, United States Department of the Interior, page 2

      • The actual formation of gemmules by fresh-water sponges is so clearly an adaptation to seasonal climatic changes, that at first it was reasonable to believe that seasonal alternation itself induced the gemmulation. However, conflicting reports on the relationship of gemmule production to seasonal temperature changes required that an alternative hypothesis be developed.

        1978, Patricia R[ose] Bergquist, “Reproduction and Development”, in Sponges, Berkeley, Los Angeles, Calif.: University of California Press, pages 125–126

      • Asexual reproduction in the sponge begins with the formation of small particles, known as gemmules, within the parent sponge tissue. […] Gemmule formation has been studied in a number of species, especially in E. fluviatilis […], as gemmule formation can be induced in vitro […]. Specific stages in the process of gemmule formation have been proposed based on the time-lapse microscopic study of Rasmont and De Vos (1974).

        2008, Noriko Funayama, “Stem Cell System of Sponge”, in Thomas C. G. Bosch, editor, Stem Cells: From Hydra to Man, Dordrecht: Springer, page 23

2. (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.  quotations

   Quotations

   • […] I assume that cells, before their conversion into completely passive or "formed material," throw off minute granules or atoms, which circulate freely throughout the system, and when supplied with proper nutriment multiply by self-division, subsequently becoming developed into cells like those from which they were derived. These granules for the sake of distinctness may be called cell-gemmules, or, as the cellular theory is not fully established, simply gemmules. […] Their development is supposed to depend on their union with other partially developed cells or gemmules which precede them in the regular course of growth. […] Lastly, I assume that the gemmules in their dormant state have a mutual affinity for each other, leading to their aggregation either into buds or into the sexual elements.

     1868, Charles Darwin, “Provisional Hypothesis of Pangenesis”, in The Variation of Animals and Plants Under Domestication. […], volume II, London: John Murray, […], part II, page 374

   • Curse you, you wandering gemmule, / And nail you fast in Hell! / You gave me gout and bandy legs, / You beast, you wanted a cell! / Gout, and gravel, and evil days— / (Theology speaks, shaking her head) / But there is One who knows your ways!

     1868, Alfred, Lord Tennyson, “Darwin’s Gemmule”; quoted in Christopher Ricks, “Tennyson Inheriting the Earth”, in Hallam Tennyson, editor, Studies in Tennyson, Totowa, N.J.: Barnes & Noble Books, 1981, part II (Alfred Tennyson), page 95

   • This theory [of pangenesis] appears to be as follows: That each living organism is ultimately made up of an almost infinite number of minute particles termed "gemmules," each of which has power to reproduce its kind. […] That such a complete collection of gemmules is aggregated in each ovum and spermatozoon in most animals, and in each part capable of reproducing by gemmation (budding) in the lowest animals and in plants. Therefore in many of such lower organisms such a congeries of ancestral gemmules must exist in every part of the body, since in them every part is capable of reproducing by gemmation.

     1869 September, “Difficulties of the Theory of Natural Selection. III.”, in The Month: A Magazine and Review, volume XI, London: Simpkin, Marshall, and Company, and Burns, Oates, and Company, page 278

   • According to this hypothesis [pangenesis], every unit or cell of the body throws off gemmules or undeveloped atoms, which are transmitted to the offspring of both sexes, and are multiplied by self-division. They may remain undeveloped during the early years of life or during successive generations; their development into units or cells, like those from which they were derived, depending on their affinity for, and union with, other units or cells previously developed in the due order of growth.

     1871, Charles Darwin, “Principles of Sexual Selection”, in The Descent of Man, and Selection in Relation to Sex. […], volume I, London: John Murray, […], Part II (Sexual Selection), page 280

   • Metamorphosis, in this respect, may truly be described as a process of the readjustment and rearrangement of the atoms and gemmules of the insect's frame. The variations of living beings may, in their turn, be explained by assuming an irregularity to exist in the arrangement of the gemmules which unite to form the germ of the varying form. Modified cells will give out modified gemmules, and these last will produce variations in the new being.

     1878 April, Andrew Wilson, “The Law of Likeness, and Its Working”, in The Popular Science Monthly. Supplement, number XII, New York, N.Y.: D[aniel] Appleton and Company, […], page 560, column 1

   • [M]icroscopic research has so far failed to discover any trace of Darwin's Gemmules in the blood or anywhere else. Furthermore, sheep have been docked in early life for scores of generations, yet every lamb is born with a tail. Since both parents and all of their ancestors have been docked, whence come the gemmules to produce the tail in the lamb?

     1917 August 3, Horace G. Regnart, “The Germ Plasm”, in Live Stock Journal, volume LXXXVI, number 2261, London: Vinton & Co., page 70, column 1

   • In retrospect, there were three main defects of Darwin's "pangenesis" theory of inheritance: (1) the presumption that there was a gemmule corresponding to every trait and specific to one and only one trait; (2) the idea that copies of all gemmules are transmitted to the next generation; and (3) the idea that somatic changes occurring during the lifetime of an individual could locally alter gemmules proceeding from the affected organ and then be passed to subsequent generations via gemmule replicates contained in the gametes.

     2003, Mary Jane West-Eberhard, “Darwin’s Theory of Development and Evolution”, in Developmental Plasticity and Evolution, Oxford, Oxfordshire, New York, N.Y.: Oxford University Press, page 190, column 2

(botany) Synonym of plumule (“the first bud, or growing point, of a plant embryo, situated above the cotyledons”)  quotations  examples

(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”)  quotations