PORIFERA. 415 



tion, yet there is a constant and uniform action going 

 on, which shews a living and energetic principle. 

 Dr. Grant has described his discovery of this 

 action in very interesting terms : " I put," he ob- 

 serves, " a small branch of the Spongia Coalita, with 

 some sea-water, into a watch-glass, under the micro- 

 scope : and on reflecting the light of a candle through 

 the fluid, I soon perceived that there was some intes- 

 tine motion in the opaque particles floating through 

 the water. On moving the watch-glass, so as to 

 bring one of the apertures on the side of the Sponge 

 fully into view, I beheld, for the first time, the splen- 

 did spectacle of this living fountain, vomiting forth 

 from a circular cavity, an impetuous torrent of 

 liquid matter, and hurling along, in rapid succession, 

 opaque masses, which it strewed every where around. 

 The beauty and novelty of such a scene in the 

 animal kingdom, long arrested my attention, but 

 after twenty-five minutes of constant observation, I 

 was obliged to withdraw my eye from fatigue, with- 

 out 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, some- 

 times observing it for a quarter of an hour at a time ; 

 but still the stream rolled on with a constant and 

 equal velocity." The water which is thus poured 

 from all the large apertures of the mass, is doubtless 

 received through the minute pores, and having con- 

 tributed aliment to the body, is discharged, exhaust- 

 ed of its nutritive matter. 



