394 Mr. Hodd's Observations on the Spongilla fluviatilis, 
Sponge, which constitute the mouths or entrances to the wider passages or 
canals formed in that structure by the anastomosing fibres, and which are 
precisely similar to those seen in a number of the Marine Sponges, and have 
been named by Dr. Grant the fecal orifices, I have here called oscules (oscula), 
—a term previously used by Ellis and Solander and by Pallas to designate 
them,—because I consider the Spongillæ, being vegetable productions, cannot 
possibly have any feeces to discharge. Although the ejectamenta, or little 
pieces of soil before alluded to, are principally the fzeces not of the Spongilla, 
but of certain animals parasitically nestling within it: these have been also 
mentioned by Dutrochet, and described by him as * des fragmens de la matiére 
caséiforme :” they are usually of a brownish colour, and are conveyed from 
the canals with the expelled current of water. On placing a living specimen 
of the Spongilla as naturally attached to a stone, or piece of wood, &c. in a 
basin of pure water, these ejectamenta may be in a little time perceived freshly 
washed out of the canals, aud resting on the surface about its oscules. "They 
are most conspicuous on looking at the Sponge in the morning (having on the 
previous night changed the water), when the whole specimen is generally 
covered by them, and is rendered quite dirty and discoloured. Washing the 
Sponge, by letting some fresh water run over it, I again noticed after a few 
hours more the same appearances. And on examining the specimen, I dis- 
covered the presence of some insect or other animal, and found that these 
ejectamenta were partly its excrementitious discharges, and partly bits of 
broken fibres, and particles of the Sponge, which were loosened by the gnaw- 
ing or burrowing of the same creature. I never observed these ejectamenta 
upon any fresh specimen wherein I was unable to detect any strange animal. 
Much the same sort of brownish excrement I have seen as emitted by the nu- 
merous polypes of Plumatella repens*, when I have kept them in a glass vessel 
filled with water for the purpose of studying their habits and organization. 
Now; as to the fancied irritability, or powers of contraction and dilatation of 
this species of Spongilla, numerous experiments have convinced me that they 
* The lik l iring À 
e experiment of d some magnesia powder on the surface of the water wherein is 
— 2 5 of = Zoophytes, will demonstrate, in the same way, that eddies and cur- 
pow on whenever any of the minute pol hi ; 
membranous dwellings, See antè, p. 390. polypes have protruded themselves from their 
