C 470 ] 
Mufclc, that, by applying itfelf exadly with its Cir- 
cumference to a fmooth and perpendicular Surface, 
enables the Infed to make its Way in fuch Cafes. At 
the other Extremity of the Body, is an oblong Open- 
ing, the greater Diameter of which runs parallel to 
the Length of the Animal, and this gives Paffage to 
the Excrements, 
But there is nothing more remarkable than the 
great Artery in thefe Worms. This Veffcl, which 
the famous Malpighi looked upon as a Chain of 
Hearts, and which in Caterpillars , as well as in many 
other Infeds, extends itfelf in a ftrait Line all along 
the Back, is here more or lefs folded in different 
Parts of its Extent 5 from one End to the other, it 
is often nothing but Folds and Doublings : Through 
thefe crooked Paffages, creeps along a Liquor ana- 
logous to Blood ; from Moment to Moment you 
may fee a Drop of that Liquor, which, fetting out 
from the Extremity of the Tail, runs fuccefliveJy 
through all thofe Windings, and at laft lofes itfelf in 
the Brain. It is eafy to trace it moft Part of its Way, 
by the alternate Motions of Contradion and Dila- 
tation, which are fucceflively excited from Ring to 
Ring. It feems as if every Part of this Artery, com- 
prehended in the Breadth of one of thofe Rings, is 
really a complete Heart, which pufhes on, to that 
which follows next, the Drop of Liquor it has juft 
received from that which precedes it. One can 
hardly be tired with Admiration of the Appearance 
which thofe continual Motions of Syftole and 'Dia- 
ftole afford : But the better to perceive it, one fhould 
fix one’s Eyes upon the Middie of the Body, where 
the Artery is largeft in Diameter ; for towards the Two 
Ex- 
