7.--SEM photos (A) Spongilla lacustris, gemmulosclere, (B) Spongilla lacustris, microscleres, (C) Spongilla lacuslris, megaclere, (D) Spongilla lacustris, gemmule
, (E) Trochospongilla horrida, gemmulosclere, (F) Trochospongilla horrida, megasclere, (G) Trochospongilla horrida, gemmule
Sorbitol dehydrogenase activity was undetectable in the quiescent gemmules
. During gemmule
germination at 20 [degrees] C, activity increased dramatically to a maximum of 0.2 [micro]mol/min [multiplied by] mg protein at 36 h [ILLUSTRATION FOR FIGURE 4 OMITTED].
In the fall and winter months, the larger framework of the sponge deteriorates and gemmules
This is also a wonderful example of what Karl Popper (1963) called "conjecture and refutation," an intellectual process whereby ideas related to the underlying principle (in this case the gemmules
of pangenesis) are proposed and then subjected to experiment in an attempt to reject them.
are asexual reproduction structures of continental sponges produced in dry and otherwise adverse periods of the year (Frost, 1991; Volkmer-Ribeiro and Pauls, 2000).
Nor could he describe how gemmules
were modified, how they were "thrown off," or even what they were.
Existence d'une regulation biochimique de l'eclosion des gemmules
chez les spongillides.
It is, indeed obvious that the presence of gemmules
in the blood can form no necessary part of my hypothesis; for I refer in illustration of it to the lowest animals, such as the Protozoa, which do not possess blood or any vessels; and I refer to plants in which the fluid, when present in the vessels, cannot be considered as true blood.
Sponge identification is based largely on spicule morphology and care was taken to collect specimens bearing gemmules
, as well as somatic tissue.
His theory of pangenesis, for example, states that each part of the adult body produces gemmules
that make their way into the sexual organs for reproduction; in this way, traits acquired by adults can be passed on to their young.
* Megascleres Gemmoscleres Gemmules
Length Width Length Width Width Min 259 22.94 48.47 9.62 690 Max 336.70 65.49 157.25 34.04 998.20 Ave 307.68 45.94 87.20 25.09 839.43 SD 20.53 7.81 23.05 4.46 72.42 * MCN-POR: 7860 3533, 3534.
the board, with Dalton's odd atoms, Darwin's gemmules