283 
Nature of the SpongiilaJHahilis. 
within the ovum, to project beyond its surface. This renders it 
probable that all the spicula, even the naked groups, projecting 
round the pores and orifices, were originally formed within the 
surface of the soft matter. Analogy leaves no doubt, that these 
ova or spherical portions of gelatinous matter, when ready to 
separate from the parietes of the canals, are delivered by the 
currents through the large fecal orifices as in the marine 
sponges ; but I have not detected any cilise on their surface, 
nor seen them swim about by their own spontaneous motions, 
like many marine ova, before fixing themselves. The ova were 
nourished only with rain water, while the spicula were succes- 
sively forming in their interior ; which show 7 s that these simple 
gelatinous globules, in which neither vessel nor fibre are discer- 
nible, have the power of secreting siliceous tubes from that pure 
element. 
The Spongilla friahilis has thus a close resemblance to the 
marine sponge in its siliceous spicula, gelatinous matter, granu- 
lar bodies, pores, internal canals, fecal orifices, currents, fecu- 
lent matter, and general mode of growth, whether in the state 
of an ovum, or in the adult state ; and, as the transition from the 
sponge to the Aicyonium by a new genus has been shown else- 
where, we have thus a regular and beautiful gradation from 
this simple substance, to the most complex polypifemus zoo- 
phytes. Although in every respect a sponge, it has a more im- 
perfect structure than any of the marine species, which is obser- 
vable in the sameness and feeble attachment of the spicula, in 
the great size and defenceless state of the pores and fecal ori- 
fices, in the general looseness of its surface and internal texture, 
— in the softness of its gelatinous matter, — in the want of cilise 
and spicula in its ova, indeed in every individual character. 
From this greater simplicity of structure, we are forced to con- 
sider it as more ancient than the marine sponges, and most pro- 
bably their original parent ; and, as its descendants have greatly 
improved their organization, during the many changes that have 
taken place in the composition of the ocean, while^he spongilla^ 
living constantly in the same unaltered medium, has retained 
its primitive simplicity, it is highly probable that the vast 
abyss, in which the spongilla originated and left its progeny, was 
fresh, and has gradually become saline, by the materials brought 
