5& OPINIONS AND DISCOVERIES 



a time, in perfect quietness, we distinctly see, tliey tell us, 

 all its apertures agape, and the currents wliich traverse 

 them. But if we irritate the animal, or remove it an in- 

 stant from the water, the currents relax or are stopped, and 

 the oscula contract, by slow and imperceptible degrees, un- 

 til they ai'e almost completely closed.* 



Grant and Audouin and Milne-Edwards always speak 

 of the sponge as an animal, without any misgivings of its 

 correctness, while the contrary Mas so evident to Link, the 

 celebrated Professor of Botany in Berlin, that, even with 

 a knowledge of the English naturalist's investigations, he 

 proposed to remove the entire family of sponges to the 

 Algse. (1831.) For ten or twelve years previously he had an- 

 nually found seeds, or very distinct sporangia,t in the Spon- 

 gilla. They are as large as millet-seed, are very visible 

 to the naked eye, and are found in minute hollows formed 

 by the net-work of their support : their number is very 

 great, but in each hollow there is just a single sporangium 

 fitted exactly to it Hence we conclude that these bodies 

 cannot be parasites. They are globular, marked some- 

 times with a dimple resembling a cicatrix. Their colour 

 is yellowish-green, and the fii'mness of their envelope is con- 

 siderable. When we break these receptacles of the seeds, 

 and view them through a high magnifier, we perceive that 

 the seeds are plunged in a soft mass laid on a gelatinous 

 membrane, which is reticulated or forms a filleted work : 

 when dried the mass assumes the appearance of a crust 



• Recherches pour servir a I'liistoire natiirelle du Littoral dela France, 

 i. p. 76-8. Paris, 1832. 



I The Sporangium is defined by Professor Liridley to be tbe exter- 

 nai case of the seeds of Lycopcrdoii and its allies. Introduction to Bo- 

 tany, p. 209. 



