882 Scientific Intelligence Zoology. 
smoothens these passages for the small streams. Every part of 
the gelatinous matter is covered with minute granular bodies, 
which are distinctly seen in every species of sponge by the weak- 
est magnifier of the microscope. These granular bodies are re- 
presented in the plates of Donati, of a spherical form, adhering 
to the quadriradial fibres of what he has named the Alcyonium 
primum Dioscoridis. They are quite invisible to the naked eye ; 
they escape along with the gelatinous matter, and compose the 
greater part of it ; they are connected with each other by the 
gelatinous matter, and probably through the same medium have 
some connection with the spicula along which they are placed. 
No part in the organization of the sponge is more constant and 
obvious than these granular transparent bodies, lining the in- 
terior of every canal from the pores to the fecal orifices. Their 
form is not quite spherical, but somewhat lengthened or ovoidal, 
and they are always attached by one extremity to the gelatinous 
matter, while their opposite end is seen to project free into the 
cavity of the canals. Through the greatest magnifier of the mi- 
croscope, no difference can be detected in their forms in different 
species of sponge ; they all appear to be enlarged and rounded 
at their free projecting extremity ; and, when watched with at- 
tention, we distinctly perceive that they possess some power of 
spontaneous motion, both when in connection with the sides of 
the canals, and when lying isolated at the bottom of the water. 
The ova of the sponge are quite visible to the naked eye, and 
are seen disseminated through the whole texture of the animal 
in the winter season. They are bodies of a yellow colour, some- 
what translucent, pear-shaped, tapering more or less at their 
narrow end in different species ; their whole outer surface is co- 
vered with delicate projecting cilise ; and when viewed through 
the microscope, in connection with the parent, we see that the 
rapid vibration of these cilise produces a distinct current in the 
water immediately around them, flowing always from their 
rounded free end, towards their tapering fixed extremity, thus 
assisting the small granular bodies in producing the currents of 
the sponge, during the period of their attachment to the body. 
They separate from the canals, and are propelled through the 
fecal orifices early in spring. None of these ova are seen in the 
sponge in summer, though we can detect no difference in the ve- 
