We will set out with the fact already noted in passing, that after repeated spontaneous fissions have changed the original fertilized germ-cell into that cluster of cells which forms a Gemmule or a primitive ovum, the first contrast which arises is between the peripheral parts and the central parts.
"Essays: Scientific, Political, & Speculative, Vol. I"
Herbert Spencer
Specimens of Spongilla crateriformis taken in a certain tank in Calcutta during the cold weather had the majority of the skeleton-spicules blunt, while the extremities of the Gemmule-spicules were distinctly differentiated.
"Freshwater Sponges, Hydroids & Polyzoa"
Nelson Annandale
Specimens of the same species taken from the same tank in July had the skeleton-spicules pointed, while the extremities of the Gemmule-spicules were much less clearly differentiated.
"Freshwater Sponges, Hydroids & Polyzoa"
Nelson Annandale