OF THE NATURE OF SPONGES. 47 



the sponge fully into view, 1 beheld, for the first time, the 

 splendid spectacle of this living fountain vomiting forth, 

 from a circular cavity, an impetuous torrent of liquid mat- 

 ter, and hurling along, in rapid succession, opake masses, 

 which it strewed everywhere aroimd. The beauty and no- 

 velty of such a scene in the animal kingdom, long arrested 

 my attention, but, after twenty-five minutes of constant ob- 

 servation, I was obliged to withdraw my eye fi-om fatigue, 

 without having seen the torrent for one instant change its 

 direction, or diminish, in the slightest degree, the rapidity 

 of its course. I continued to watch the same orifice, at 

 short intervals, for five hours, sometimes observing it for a 

 quarter of an hour at a time, but still the stream rolled 

 on with a constant and equal velocity. About the end of 

 this time, however, I observed the current become percep- 

 tibly languid, the opake flocciili of feculent matter, wliich 

 were thrown out with so much impetuosity at the begin- 

 ning, were now propelled to a shorter distance from the 

 orifice, and fell to the bottom of the fluid within the sphere 

 of vision ; and, in one hour more, the current had entire- 

 ly ceased."* 



From numerous experiments on many species, Dr Grant 

 infers that all sponges in a living state exhibit this sort of 

 circulation, — imbibing the untainted water by the pores,t 

 and propelling it in regular currents through the wide ca- 

 nals and fecal orifices. | The health and nutrition of the 



• Jameson's Ediii. Phil. Joiini. xiii. p. 102. 



f Lib. cit. xiv. p. 117 : also Outlines of Comp. Anat. p. 310-312. 



^ In some sponges there are no obvious orifices (oscula) distinct from 

 the pores, but " as currents of water pass through the body of every liv- 

 ing sponge, from the surface towards the interior, the same currents are 

 continually flowing from the interior to the surface by difTerent pasages ; 



