These bodies have no relation whatever with the production of the eggs or
gemmules, as they are formed before th young polypi appear in the cells at the end of the growin branches; as they move independently of the polypi, and d not appear to be in any way connected with them; and a they differ in size on the outer and inner rows of cells, I hav little doubt, that in their functions, they are related rathe to the horny axis of the branches than to the polypi in th cells.
8.--SEM photos (A) Trochospongilla leidii, gemmulosclere, (B) Trochospongilla leidii, megasclere, (C) Trochospongilla leidii,
gemmuleTherefore, Harvey conceived development as a gradual process of generation and growth starting from a homogeneous substance and driven by a plastic power: "In the egg then, as we have said, there is no distinct part or prepared matter present, from which the foetus is formed; but in the same way as the apex or
gemmule protrudes in a seed; so in the egg, there is a macula or cicatricula, which endowed with plastic power, grows into the eye of the egg and the colliquament, from which and in which the primordial or rudimentary parts of the chick, the blood, to wit, and the punctum saliens are engendered, nourished, and augmented, until the perfect chick is developed" (Harvey, 1847, p.
The effect of cadmium and mercury on
gemmule formation and gemmosclere morphology in Ephydatia fluviatilis (Porifera: Spongillidae).
Choosing a desirable plant density as for the continental conditions of region cause better
gemmule establishment, more effective use of light, nutrients and environmental factors, better competition against weeds and finally more yield increase [10].
Synergy between low temperature and desiccation in breaking
gemmule diapause of Eunapius fragilis (Leidy).
Directional translocation of cells and nutrients occurs in
gemmule formation (Rasmont and de Vos, 1974) and during oogenesis (Fell, 1983), but this transport occurs over very short distances.
Typically, spicule and
gemmule morphology are used as key identifying morphometries, but accurate identification can be challenging due to the degree of similarity between spicule and
gemmule structure and the absence of
gemmules in some species (Ricciardi and Reiswig, 1993; Manconi and Pronzato, 2008).
Gemmulation,
gemmule hatching and sexual reproduction in fresh-water sponges.
(5) Darwin even proposed a Lamarkian form of inheritance called
gemmules which gave a kind of environmental feed back into the genome of organisms (Darwin, C.
Hatching of freshwater sponge
gemmules after low temperature exposure: Ephydatia mulleri (Porifera: Spongillidae).