EN 1OZOA. 867 
In summer, when the water of the sea is warmed hy the heat of the sun 
they float upon the surface, and in the dark they send forth a kind of shining 
light, resembling that of phosphorus. 
They are often seen fastened to the rocks and to the largest sea shells, as 
if to derive their nourishment from them. If they be taken and put into 
spirit of wine, they will continue for many years entire; but if they be left 
to the influence of the air, they are, in less than four and twenty hours, 
melted down into limpid and offensive water. 
In all of this species, none are found to possess a vent for their excre: 
ments, but the same passage by which they devour their food serves for the 
ejection of their feces. These animals, as was said, take such a variety of 
figures, that it is impossible to describe them under one determinate shape ; 
but, in general, their bodies resemble a truncated cone, whose base is applied 
to the rock to which they are found usually attached. Though generally 
transparent, yet they are found of different colors, some inclining to green, 
some to red, some to white, and some to brown. In some, their colors ap- 
pear diffused over the whole surface; in some, they are streaked, and in 
others often spotted. They are possessed ofa very slow, progressive motion, 
and, in fine weather, they are continually seen stretching out and fishing for 
their prey. 
CLASS XI.—ENTOZOA. 
Body soft, elongated, naked in almost all, without head, eyes, or feet ; mouth 
formed of one or many suckers ; no tentacula or organs of respiration ; tn- 
testinal canal in some scarcely perceptible. 
THE intestinal worms are remarkable for existing and propagatmng only 
m the interior of animals. There is scarcely an animal in which there are 
not found some species of parasitical worm ; and they occur not only in the 
alimentary canal and the vessels which communicate with it, such as the 
hepatic vessels, but even in the cellular tissue, in the liver, and the brain. 
The difficulty of conceiving how they appear in these parts, joined to the 
cbservation, that they are never found but in living bodies, had led some 
naturalists to suppose that they were engendered spontaneously. It is, 
however, now ascertained, not only that the greater part produce ova or 
living young, but that many have separate sexes, and couple as ordinary 
animals. These worms or ova, however, must be of extreme minuteness to 
be able to pass through channels so narrow. 
The intestinal worms being destitute of trachea, bronchie or any other 
organ of respiration, must necessarily receive oxygen through the medium 
