ENTOZOA. 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 foeces. 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 of a 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 ; in- 

 testinal canal in some scarcely perceptible. 



The intestinal worms are remarkable for existing and propagating only 

 in 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 

 observation, 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, bronchise or any other 

 organ of respiration, must necessarily receive oxygen through the medium 



