SPONGE-FISHING. 
547 
as a shining, blackish, fleshy lump, which cuts like raw meat, no trace of the 
horny network being visible. The discovery would probably result from finding 
cast up specimens with the skin and flesh partly rotted away from the more 
durable skeleton. A toilet-sponge when alive is a blackish, cup-shaped fleshy 
mass, with its surface covered with minute conical elevations. In the hollow of the 
cup are the oscules, which appear smaller than in the skeleton, and are capable of 
dilating and contracting. During life currents rush out of these holes. On the 
outer surface of the sponge, by very careful inspection, sieve-like groups of pores 
will be seen in the skin, between the conical elevations. 
When a living sponge is torn or cut, a good deal of glutinous substance flows 
away. The dark skin covers a light yellow fleshy substance, in which the canals 
leading to the oscules are conspicuous. The walls of the canals are greyish, some 
being filled with mud, others containing a marine-worm or crust¬ 
acean, others, again, being empty. The skin-pores open into sub- 
dermal spaces beneath, and from the floor of the latter canals 
branch into the body-substance. The smallest canals finally 
open into minute pyriform flagellated chambers; and from each 
of the latter there arises a rootlet of the out-current canal- 
system. What is commonly known as the sponge forms a 
supporting network of fibres in the gelatinous ground-substance, 
the horny skeleton forming a kind of scaffolding. The fibres 
are yellowish and translucent, and built up of concentric layers 
surrounding a thin axial thread. Foreign particles, such as 
sand-grains, flinty spicules of other sponges, etc., are included 
in the main fibres. Each growing fibre is surrounded by 
cylindrical cells which secrete it. When a fresh batch of 
cells secretes a new layer, foreign particles on the surface of 
the fibre become included within the new coating. The 
embryos are minute oval bodies, which swim by means of 
their cilia, and lead an independent life for a day or two. 
They then settle down by becoming fixed at one end, and 
develop into sponges. 
In addition to sexual reproduction, there is also vegetative 
propagation. This characteristic has been made use of for cultivating sponges by 
Ascetta primorcUalis. 
After Haeckel. 
cuttings. 
Sponge-Fishing. 
Sponges are found in depths ranging from two to one hundred fathoms, and 
the methods of collecting depend both on depth and locality. Off Dalmatia the 
primitive method of harpooning is still employed. Two men go out in a small 
boat; one rows, the other leans over the edge holding a long fork. If the water 
ripples, the rower throws in a half circle in front of him a few pebbles dipped in 
oil. The Greeks employ a submarine spyglass, which simply consists of a pane 
of glass let into the bottom of a tube or bucket. By this means they do away with 
the effect of the surface ripples. In the Levant in depths of five to fifty fathoms 
divers are employed, either naked or provided with a diving-dress. In the former 
