548 SUPPLEMENT 
and Rondelet, we derive nothing in addition to what the 
ancients have left us; and Gesner and Aldrovandus, who 
compiled with so much patience, and frequently with so much 
sagacity, all that had been said by their predecessors, one in 
an alphabetical, the other in a systematic form, have col- 
lected nothing new respecting the worms, and more particu- 
larly respecting the intestinal ones. 
It was only, in fact, towards the end of the seventeenth 
century, that the science of helminthology may properly be 
said to have had its birth, and this birth took place in Italy, 
the mother of almost all modern art, science, and literature. 
To that country belong the names of Redi, Malpighi, and 
Vallisnieri. 
The popular name of worm, under which these animals 
have been included, sufficiently indicates that their body is 
almost always cylindrical, more or less elongated, attenuated 
at the two extremities, and of a diameter infinitely less than 
the length. In some the body is more perfectly cylindrical, 
in others sacciform. Even a certain number resemble 
bladders, as the hydatids; or very depressed lamine, as the 
fasciole, &c. Whatever be its form, it is always perfectly 
symmetrical, as in all other binary animals, and most fre- 
quently the dorsal face may be distinguished from the ventral, 
by a little more convexity in the former than the latter. 
It is but seldom that we can trace in the body of these 
animals the distinction of head, neck, belly and tail. Never- 
theless, it sometimes happens that the anterior extremity is 
enlarged, and is well distinguished from the rest of the body, 
and then the animal is provided with a cephalic enlargement, 
as in tenia, &c. But most usually the body, attenuated in 
front, swells out by degrees, and again becomes attenuated 
at the posterior extremity. 
In many of these animals articulations may be observed, 
but they are sometimes extremely indistinct. In other cases 
