337 
and Functions of the Sponge. 
fcion of the fact ; and as Mr Ellis has been proved above to be 
wrong in the most material part of his statement, regarding 
the direction of the currents ; he may likewise have fallen into 
some mistake, in what he has alleged concerning the motions of 
the fecal orifices. 
I first selected a large entire specimen of the Spongia pani- 
cea from a basin of sea- water, in which I perceived it propel- 
ling its feculent matter very briskly, and, along with that mat- 
ter, occasionally discharging those singular moving round bo- 
dies, which I have termed above the Ova of the Sponge, in 
compliance with the nomenclature of naturalists, for similar 
moving bodies, which have proved to be the germs of other zoo- 
phytes. As this sponge has always few and very large fecal ori- 
fices lying on a level with the general surface of the animal, it 
is well calculated for examining the singular properties of suc- 
tion, palpitation, systole and diastole, which have been so gene- 
rally ascribed to these orifices. Having placed this lively spe- 
cimen in a shallow vessel, filled with clear sea-water, and in a 
favourable light, for looking down into its aperture, I observed 
it attentively, for a quarter of an hour, with the naked eye ; and 
afterwards, for nearly the same length of time, through a pocket 
lens, but could not detect the slightest contraction or palpita- 
tion, nor the most languid motion of the orifice, over which the 
lens rested, although the stream continued to flow quickly from 
it, without interruption, during the whole time. I now let fall 
a dark coloured grain of basalt into the orifice of this bright 
yellow sponge, and looked sideways upon it, in such a position, 
that the grain was only half seen over the margin of the aper- 
ture ; the slightest dilatation would have brought the whole of 
the grain into view, and the slightest contraction would have 
immediately concealed it from me ; but though attentively ob- 
served, for ten minutes, with the head fixed in one position, the 
grain remained constantly in the same situation, just half seen, 
over the margin of the orifice. In another living specimen of 
the same kind of sponge, I tried to force the aperture to con- 
tract, by piercing and irritating its parietes with a sharp needle ; 
and after pouring off a little of the sea- water, I touched the vi- 
cinity of the aperture with a red-hot wire, without producing 
the smallest change in the dimensions of the orifice. In all the 
