Sexual cells. The polyps are unisexual; the colonies are of different sex. The largest 
number of species have their sexual cells in the primary transversal mesenteries, but in one 
species ( Eucirr. contoria) there are very well developed ovaria to be found in the anterior 
pair of secondary mesenteries _ and even in the sixth pair of secondary mesenteries. Perhaps 
there are ova to be found in the anterior sagittal mesenteries but this is very uncertain and 
highly improbable. However the ovaria are always best developed in the primary transversal 
mesenteries. The mesogloea of the ovaria-bearing mesentery is dissolved in fine fibres in the 
fertile part of the mesentery, surrounding the ova (but not the ovaria) with a very thin meso- 
gloeal capsule, which is much thicker for the testes-follicles. The ova may have a thicker 
capsule, but rarely, as in Sibopcithes gephura. The collapsed state of some capsules indicates 
the liberation of the, ova by the bursting of the capsule. The youngest ova are found in the 
neighbourhood of the mesenterial mesogloea, near the ovarial limits. The ovaria are developed 
unilaterally, which may especially be noted in the secondary mesenteries. 
The thick mesogloeal capsule of the testes-follicles is in connection with the mesenterial 
mesogloea. This capsule is thinner as it is nearer the epithelial surface of the mesentery; in 
this case the connection with the mesogloea of the mesentery is not always well visible and 
the ripe testes are surrounded especially by epithelium. The spermatozoa may be liberated into 
the gastral cavity by the bursting of the capsules, but in other cases I saw the spermatozoa 
pass through the invagination-opening of the mesenterial mesogloea, which gave origin to the 
capsule; this opening was probably the primitive one but may perhaps also be a secondary 
one. — In one case I saw free testes-capsules in the gastral cavity near the mouth. — The 
tails of the spermatozoa are arranged in a cylinder or fan-shaped; this bundle may be composed 
of secondary bundles. With some species I saw the tails all of them directed towards the 
mesenterial mesogloea. 
As to the mode of origin of ovaria and testes, it is to be remarked that the sexual 
cells are of entodermal origin; they are found in the entoderm on the same side of the mesen¬ 
teries as the longitudinal musclefibres. The mesogloea below these cells invaginates into a 
capsule, which in this manner is after all found on the same side of the mesentery as the 
transversal musclefibres, where they remain definitively. The capsules may remain connected 
with the mesenterial mesogloea as is very often the case with testes as well as for ova. In the 
case of testes I have seen this stalk of the capsule remain open (or being secondarily opened) 
for the passage of the ripe spermatozoa ; in the case of ova I have seen the opening of the 
invagination but rarely. — The unilateral swelling of the mesenteries and the S-shaped folding, in 
which the swelling results, I have discussed more extensively on p. 227 and figured in fig. 261. — 
A hen the unilateral development is not immediately visible, it may be deduced from secondary 
facts, such as the occurrence of ova in the base of only one lateral tentacle of the same pair, 
etc. — As a remarkable deviation I found testes in the entoderm of the bodywall, near the 
place of attachment of the primary transversal mesenteries, and even in the ectoderm of the 
tentacles, probably while the mesogloeal invagination transferred the testes from the entoderm 
towards the ectoderm (cf. S tichopathes variabilis , p. 233); in the bodywall the mesogloea was 
too thick to invaginate, but the mesogloea at the tentacle-top is much less resistent. 
