£82 Dr Grant on the Structure and 
form, within the living spongilla, in the parenchymatous soft 
substance, between the internal canals. They appear to be the 
ova or germs of this substance, — they contain no spicula,-— and 
the microscope detects nothing in their structure but transparent 
granular bodies, like those lining the canals, connected together 
by gelatinous, homogeneous matter. During October and No- 
vember, several of these spherical, translucent, greyish-green co- 
loured globules, attached themselves to the bottom of watch- 
glasses, in which I had placed broken portions of spongilla, and 
when fixed, they spread, and exhibited the same phenomena of 
growth, presented under similar circumstances by the ova of the 
marine sponge. They are not quite so large as the yellow car- 
tilaginous balls of the spongilla, above described ; and, when 
they first lose their spherical form, and begin to spread on the 
glass as a thin, transparent film, we distinctly perceive, even with 
a single lens, that they contain no spiculum. With the micro- 
scope we can observe the position, size, and form of each spicu- 
lum, as they successively make their appearance in the spread- 
ing circular film. The spicula first formed were generally two 
or three, lying close and parallel to each other, and extending 
from the centre towards the margin of the ovum. Afterwards, I 
observed single spicula make their appearance, quite isolated, in 
different parts of the ovum, and often at right angles to the ra- 
dius of the place where they lay. The radiating double spicula 
are probably the beginnings of the longitudinal, erect fascicula ; 
and the others the single transverse spicula. The spicula first 
formed in the ovum have the same form as the adult spicula, 
and appear greatly disproportioned to the small size of the 
ovum. I have never observed a spiculum enlarge by growth, 
after being once formed. The ovum, in spreading, changes its 
circular form for an oblong or irregular outline, but its spread- 
ing margins are always surrounded with a very thin homoge- 
neous film, while its granular bodies and spicula occupy chiefly 
the convex middle part. I have observed, however, spicula 
quite isolated make their appearance in the spreading marginal 
film. None of the spicula are ever observed to shoot their 
points naturally through the surface, or beyond the margin of 
the ovum ; although the slight agitation of changing its water 
from time to time, soon causes many of them, already formed 
