398 Prof. J. Reid on the Anatomy and 
cured about the middle of October, these ovary-capsules were 
more or less filled with opake bodies (ovaries) of a slightly yel- 
lowish colour. Each of these bodies was composed of small 
nucleated cells inclosed in amembrane. The external surface of 
this membrane was in many of them provided with cilia in mo- 
tion, causing some of them to perform a rapid rotatory motion 
within the ovary-capsules. These ova in the first stage of their 
growth adhere to,the upper end of the lining membrane of the 
capsule. This ining membrane stretches across the aperture in 
the capsule, and also sends a reflection across the cell imme- 
diately below the ovum so as to inclose it ma kind of sae, leaving 
however, in the young ovum, a space between them. In the more 
advanced ova, this membranous partition was much thickened, 
especially at the central part, forming a considerable projection 
in the direction of the aperture in the capsule, and contained a 
number of nucleated cells.. When the ovum enlarges so as to 
fill the interior of the capsule, it pushes this membranous parti- 
tion before it. This membrane was observed in a few instances 
where the ova were fully formed to contract and relax at in- 
tervals, and in this way it may assist in the escape of the ovum. 
On detaching some of the ovary-capsules with the view of ex- 
amining their contents under a high power, one of the ova was 
seen partially extruded from the aperture in the capsule. It 
was divided by a deep fissure into two unequal parts, the 
largest of which was nearly entirely outside the capsule (fig. 
13 a). The extremity of the largest portion (fig. 18 ¢) was di- 
stinctly prolonged, more translucent than the rest of the ovum, 
and presented along its free edge a row of hairs resembling 
cilia, which, however, remained quite motionless, while along the 
whole of the rest of the external surface of both portions, exeept 
upon the edges of the fissure, cilia were in such vigorous action 
that it was impossible to distinguish them imdividually, and they 
produced the appearance of the rim of a wheel in very rapid 
rotation. After the lapse of an hour the fissure had extended 
through the whole body of the ovum, and the larger portion (fig. 
13 b) being set free, swam about very actively in the water; but 
all this time the hairs attached to the prolonged anterior portion 
remained motionless. The smaller portion continued in the cap- 
sule, and performed very rapid rotatory movements. This was 
the only ovum I observed in the act of escaping from the inte- 
rior of the capsule, but I had an opportunity of watching three 
other bodies exactly similar to the larger portion of the ovum 
already described, when examining other portions of the same 
polypidom. One of these had become fixed, by the hairs attached 
to the anterior extremity, to a minute portion of sea-weed, and 
the cilia were in active motion. When examined ten hours after, 
