77 7 JOURNAL OF THE 
Some sponges are known to be hermaphrodite, others 
have been described as of separate sexes. The preba- 
bility is that sponges are in general hermaphrodite, but 
that the individual at one period produces chiefly male 
elements, and later chiefly female elements. Fer tiliza- 
tion takes place in the body of the mother and the egg 
here undergoes early development. The embryo even- . 
tually bursts the maternal tissue, and, passing into 
one of the canals, is caught by the current sweeping 
through the canal system and is discharged into the sur- 
rounding water through one of the large apertures 
(oscula) on the surface of the sponge. 
In the great majority of sponges (horny and silicious 
forms) the embryo, or larva as it now should properly be 
called since it leads a free life, is an oval, solid body, 
covered with slender hair-like processes of protoplasm, 
the so-called cilia. The cilia strike rythmically to and 
fro, like so many minute and flexible paddles, and the 
sponge larva is by their means whirled through the 
water. Soonge larvae, of course, vary in size, but 
frequently have a length in the neighborhood of 1 mm, 
(.04 inch). The surface layer contains more or less pig- 
ment. Thusin the commercial sponge, Husfpongia, the 
larva is whitish, with a brown spot at one end. In 
Tedani brucei, a large red sponge, growing especially oz 
the mangroves in parts of the Bahamas, the larvaisa 
beautiful red. 
The free swimming life of the sponge larva is short last- 
ing, when bred in the iaboratory,only a day or two. During 
this period the larvais moved not only by its own relative- 
ly feeble motion, but, being subject to the action of the 
currents, it may be carried a considerable distance from 
the spot where it was born. It eventually settles down 
on some firm basis and transforms. ‘The cilia are lost, 
and the oval body flattens out into a disk so thin that it 
