S3 6 Dr Grant’s Observations on the Structure 
admit water into the interior of the body, or as common orifices 
through which polypi occasionally shoot out their heads. Pal- 
las has introduced the systole and diastole, ascribed to these ori- 
fices by his predecessors, into his definition of this animal, and 
Cuvier has copied this singular phenomenon of the living sponge, 
as an established fact, into his Kegne Animal. 
In a subject like this, which has defied the researches of na- 
turalists for a period of three thousand years, it is an important 
step towards the discovery of truth, to examine minutely the ac- 
curacy of all statements and opinions already entertained regard- 
ing it, whether supported by great authorities or by great anti- 
quity. It is of some importance to determine, Whether the 
living sponge has any such power of contracting and dilating the 
fecal orifices ; because such a property might have much influ- 
ence in the mysterious functions of this animal ; or a belief in its 
existence might lead to an erroneous opinion of the uses of these 
orifices, or might interfere with the true explanation of the cur- 
rents which flow from them. It is likewise important to inquire 
into the existence of this property, because we have just seen 
that it has been assumed by the most eminent naturalists as a 
leading character of discrimination between the sponge and 
nearly allied genera of zoophytes. 
It has been already shewn, by the above experiments, relative 
to the direction and force of the streams, that the currents never 
flow into the fecal orifices, but constantly, in one direction, from 
them, with a smooth and equable motion. It must therefore be 
evident, that any palpitation, or other motion, which the lips of 
these apertures might exhibit, could have no effect in producing 
the streams which flow from them, whatever function such sin- 
gular motions might perform, in the economy of the sponge. I 
must likewise observe, that those naturalists who asserted, that 
they had seen this systole and diastole, or palpitation of the fecal 
orifices, at the same time believed, that these motions had the 
most intimate connection with the streams ; that the sponge, in 
fact, sucked in and squirted out water by these orifices, as by so 
many polypi ; or, as we see Ascidise , and many bivalve mollusca , 
suck in and squirt out water by two highly contractile orifices. 
There is, therefore, some grounds for suspecting, that their pre- 
conceived errors may have had some influence on their observa- 
