86 
Donati, in his Essay on the Natural History of the Adriatic Sea, 
has made, in some respects, a more minute examination of the struc- 
ture of two different species of alcyonia than even that of Count 
Marsilli, and was enabled to ascertain by the aid of a magnifying glass, 
the peculiar forms assumed by the spines of which these animals are in 
a great measure composed. Of these we shall soon have occasion to 
speak more particularly. 
The forms in which these animals exist are very numerous ; this 
depending not merely on the number of species, but on the different 
irregular forms which the same species under different circumstances 
may assume. Thus, Marsilli observes, the same alcyonium, which some- 
times grows flat, and thus covers large pieces of rocks, is at other times 
found in a rounded form. 
From the different colours as well as forms which some of the 
species of these substances possess, they have obtained names expres- 
sive of their resemblance to certain fruits. Thus the alcyonium lyncu- 
rium, being of a globose form, of a fibrous internal structure, of a 
tubercular surface, and of a yellow colour, has been termed the sea- 
, orange : the a. bursa, being of a sub-globose form, of a pulpy substance, 
and of a green colour, has been termed the green sea-orange or sea- 
apple : the a. cydonium, which is of a roundish form, and of a yellow 
colour, has been distinguished as the sea-quince : and the a. Jicus, 
from a very close resemblance to the fig in its form, has been called 
the sea-fig. 
The sponge is a fixed, flexible animal, very torpid, varying in its 
figure, and composed either of reticulated fibres, or masses of small 
spiculae interwoven together, which are clothed with a living gelatinous 
flesh, full of small mouths or holes on its surface, by which it sucks in 
and throws out the water. 
The vitality of sponges had been suspected by the ancients, even 
in the time of Aristotle ; they having perceived a particular mo- 
tion in their substance, as if from shrinking, when they tore them off 
