ON SPONGES. 
305 
The pores in Spongiadse are, as already mentioned, the orifices 
or months through which the animals imbibe their nutriment, 
and receive the supply of water, which, in their case, is the 
equivalent of a supply of pure air for respiration to an animal 
living on land. In some of the more highly organized genera, 
there is good reason to believe they are permanent organs. 
But not so in others. The opening and closing of the pores in 
Sjpongillci fluviatilis has been described at length. Each 
operation is commenced and terminated in less than a minute ; 
they are perfectly dependent on the will of the animal, and 
in neither case are they simultaneous, but follow in irregular 
succession, in accordance with the necessities of the animal ; 
and when once closed, they do not appear to ever open again 
in precisely the same spot.-’^ ‘‘‘’No cicatrix remains for an 
instant after closing ; no indication of the spot where the 
opening is the next moment to be effected.’’^ 
The oscula are the fecal orifices of the sponge. They are 
permanent organs, and are capable of being opened or closed 
at the will of the animal, and are subject to a considerable 
amount of variation in size and form, in accordance with the 
variations in the actions of the sponge.'’^ 
Such of our readers as may be spending a little time at the 
seaside next summer, may possibly have the opportunity of 
collecting some marine sponges from the rocks, and watching 
the vigorous currents to which they give rise when placed in 
shallow vessels of sea-water. If so, they may perhaps find, to 
their surprise, that two or three specimens of the same kind of 
sponge, placed in gentle contact with each other, will, within 
twenty-four hours, be united firmly together; and on the 
ensuing day the union will be so complete that no trace of the 
junction can be detected. But not so if the specimens belong 
to different species ; then neither contact nor compression will 
compel them to unite. The following experiment, recorded by 
Dr. Bowerbank, we have more than once repeated, with some 
slight modifications. 
Seven larger sponges, which he had separated by cutting into 
halves, and then replaced in water with the divided parts 
again in close contact, were all found firmly united at ten o^ clock 
on the following morning; and next day, so early as 10 a.m., 
the reparation of the subjects of the above experiment was so 
complete as to obliterate all traces of the separation in some 
of them. In other cases he ‘^feut the same species of sponge 
into three pieces, and reversed the position of the middle 
piece of each, so as to render the sections unconformable ; but 
1862, and in vol. i. of his ‘‘Monograph of the British Spongiadce.” Eay 
Society, 1864. 
