"But how do they feed?"
"A sponge is a jelly-like colony of cells with a fibrous skeleton," the boy explained; "the outside of him is toward the water and is full of small pores which branch all through his flesh and open at last into a big pore leading to the outside. All these pores are lined with tiny hairs that make a current of water go through the jelly-like flesh, which absorbs any microscopic life there may be. The water is taken in through the little pores and sent out through the big ones. Some sponge forms are of one animal, most are of colonies. But they are all on the same pattern, pumping water in and out again."
"Then is a growing sponge all full of jelly?" asked Paul.
"All that I have seen are," Colin replied.
"How do they get it out?"
"I c'n tell you 'bout that," interjected Pete. "A sponge is all slimy an' nasty. Yo' put him in de sun an' he dies quick an' all de slime runs out. Den yo' buries him in san' 'til his insides all decay. Den you puts him in a pon' an' takes him out, an' beats him wif a stick, lots o' times oveh, maybe, 'til all de jelly an' all de san' an' all de muck am out ob him. Den yo' wash him in
fresh wateh 'til he's clean an' lets him dry an' he's done."
"But if sponges will reproduce themselves," the capitalist said, returning to his former point, "what is the need of planting them?"
"You don't have to work that way on their own beds, sir," the boy answered, "planting is done to get more out of the industry, using the sea bottom in shallow waters which now is lying unused."
"And you say only rocky land will do?"