Immediately after adhesion the young sponge flattens itself out. This process apparently presses together the water in the subdermal cavity and causes a large part of it to accumulate at one point, which is usually situated near the centre of the upper surface. A transparent conical projection formed of the external membrane arises at this point, and at the tip of the cone a white spot appears. What is the exact cause of this spot I have not yet been able to ascertain, but it marks the point at which the imprisoned water breaks through the expanded membrane, thus forming the first osculum. Before the aperture is formed, it is already possible to distinguish on the surface of the parenchyma numerous channels radiating from the point at which the osculum will be formed to the periphery of the young sponge. These channels as a rule persist in the adult organism and result from the fact that the inhalent apertures are situated at the periphery, being absent from both the proximal and the distal ends of the bud. In the case of floating buds the course of development is the same, except that the osculum, as in the case of development from the gemmule in other species (see Zykoff, Biol. Centrbl. xii, p. 713, 1892), is usually formed before adhesion takes place. The sponge of _S. proliferens_ is usually too small to afford shelter to other animals, and I have not found in it any of those commonly associated with _S. carteri_ and _S. alba_. Owing to its small size _S. proliferens_ is more easily kept alive in an aquarium than most species, and its production of buds can be studied in captivity. In captivity a curious phenomenon is manifested, viz. the production of extra oscula, often in large numbers. This is due either to a feebleness in the currents of the sponge which makes it difficult to get rid of waste substances or to the fact that the canals get blocked. The effluent water collects in patches under the external membrane instead of making its way out of the existing oscula, and new oscula are formed over these patches in much the same way as the first osculum is formed in the bud. 3. Spongilla alba*, _Carter_. _Spongilla alba_, Carter, J. Bombay Asiat. Soc. iii, p. 32, pl. i, fig. 4 & Ann. Nat. Hist. (2) iv, p. 83, pl. iii, fig. 4 (1849) _Spongilla alba_, Bowerbank, P. Zool. Soc. London, 1863, p. 463 pl. xxxviii, fig. 15. _Spongilla alba_, Carter, Ann. Nat. Hist. (5) vii, p. 88 (1881). _Spongilla alba_, Petr, Rozp. Ceske Ak. Praze, Trída, ii, pl. i, figs. 3-6 (1899) (text in Czech). _Spongilla alba_, Annandale, Rec. Ind. Mus. i, p. 388, pl. xiv, fig. 2 (1907).