XXII.— NOTES ON FRESHWATER SPONGES. 



By N. Annandai^e, D.Sc, Officiating Superintendent , 

 Indian Museum. 



I. — The Buds of Spongilla Proliferens, mihi. 



The buds that form so characteristic a feature of this species 

 arise as thickenings of the strands of cells accompanying the 

 primary spicule fibres of the skeleton, which project outwards 

 from the surface of the sponge. These thickenings originate 

 beneath the surface and contain, at the earliest stage at which 

 I have as yet examined them, all the elements of the adult or- 

 ganism {i.e., flesh spicules, ciliated chambers, efferent and afferent 

 canals, parenchyma cells of various sorts) except skeleton fibres, 

 gemmules, and a dermal membrane. A section at this period 

 closely resembles one of an adult sponge, except that the struc- 

 ture is more compact, the parenchyma being relatively bulky and 

 the canals of small diameter. 



As the bud grows it makes its way up the fibre, pushing 

 the dermal membrane, which expands with its growth, before it. 

 The skeleton fibre does not, however, continue to grow in the bud, 

 in which a number of finer fibres make their appearance, radiat- 

 ing from a point approximately at the centre of the mass. As 

 the bud projects more and more from the surface of the sponge 

 the dermal membrane contracts at its base, so as finally to separate 

 it from its parent. No aperture is left when this occurs, the 

 membrane closing up the gap completely. The newlj^ liberated 

 bud already possesses numerous minute pores, but as 5'et no 

 osculum ; its shape exhibits considerable variation, but the end 

 that was farthest from the parent sponge before liberation is 

 always more or less rounded, while the other end is flat. The size 

 also varies considerably. Some of the buds float, others sink. 

 Those that float do so either owing to their shape, which depends 

 on the degree of development they have reached before libera- 

 tion, or to the fact that a bubble of gas is produced in their 

 interior. The latter phenomenon only occurs when the sun is shin- 

 ing on the sponge at the moment they are set free, and is due to 

 the action of the chlorophyl of the green bodies so abundant in 

 certain of the parenchyma cells of this species. If the liberation 

 of the bud is delayed rather longer than usual, numbers of flesh 



