THE SPONGES. 73 
search for a suitable place where they may affix themselves. 
When once fixed, the larva loses its vibratile cils,* spreads itself 
out, and takes the form of a very flat gelatinous disc. Its interior 
organisation consists of contractile cellules and numerous spicule. 
The exact time taken by a sponge to develop is not exactly 
known ; but the sponge-gatherers return in three years to the place 
which they had cleared. 
Fishing for sponges is principally carried on by the Greeks and 
the Syrians in that part of the Mediterranean which washes the 
THE SPICULA: OF SPONGES. * 
shores of their countries. The Greeks commence their fishing in 
May and end in August, the Syrians continue to the end of Sep- 
tember. The boat’s crew consists of four or five men. Each diver 
is armed with a strong-bladed knife, or a three-pronged trident, 
curved; and a net-pouch fastened to it. The boats having arrived 
at the rocks where the sponges grow—when the sea is calm the 
polypiers are easily seen—the men commence diving for them 
* Cils or Cilia (cé//m, a hair or eyelash) are microscopic filaments, like hairs, found 
chiefly upon the surface of tissues which are in contact with water. These peculiar 
organs are distributed throughout the whole animal kingdom. They possess two kinds 
of motion, vibrating and rotating; but the movement is not produced by muscular 
action. In very small animals the cilia act as organs of locomotion, and in the larger 
animals, such as the mollusca, they produce currents of water, which bring to the 
creature its food. 
