114 Dr Grant’s Observations on the Structure 
collecting of them for the demands of commerce, forms a lucra- 
tive profession, with many on the coasts of Calabria, Sicily, and 
the Grecian islands ; and in a single voyage to the South Seas, 
nearly 100 distinct species were collected, which are preserved in 
the museums of Paris. 
If the irritability of the living sponge, therefore, has hitherto 
escaped observation, that cannot be attributed to the rarity of 
the animal, although this circumstance has been complained of 
by Mr Ellis and some other naturalists ; nor can it be ascribed 
to the smallness of the object, or the difficulty of examining it in 
its native retreats ; for several species of sponge attain, even in 
our cold latitudes, a magnitude of some feet ; and many of them 
grow so near the shore, that they are left exposed for two or 
three hours during the recess of every ordinary tide. At Leith 
and Prestonpans Bay, the Spongia urens or tomentosa is ob- 
served, in places accessible at low- water, spreading over the sides 
of rocks, and insinuating itself into all the interstices of the roots 
of fuci, without venturing to climb up along their stems ; but, in 
deep and tranquil situations, where the fuci are less agitated by 
the waves, and attain a greater size, the tomentosa attaches itself 
directly to the stems of the large Fucus palmatus, along which it 
mounts to an extent of more than three feet, with a thickness 
often exceeding an inch from the surface of the plant to the ex- 
ternal surface of the animal. It thus chokes up the superficial 
pores of these sturdy plants,— diminishes their supply of nourish- 
ment, — adds to their weight, — causes them to present a greater 
surface to the motions of the sea, and, in this exhausted condi- 
tion, the plants are less able to retain their attachment to the 
rocks, or combat with the storms, which generally wash them 
ashore in great quantity, loaded with these large sponges in the 
highest degree of vitality. Sometimes the fishermen’s dredges 
are brought up from deep water nearly half filled with bushes 
of the Spongia coalita ; and specimens of the Spongia dichoto- 
ma are sometimes dredged near Inchkeith, measuring a foot in 
length, and nearly as much in breadth. 
When two sponges of the same species come into contact with 
each other in the progress of their growth, they unite so com- 
pletely, as not only to obliterate the line of junction, but even 
communicate freely by their internal canals. Thus I have seen 
4 
