Of the Polype'j Body. 25 



Space that always remains tranfparent, even 

 when byFuUnefs, or Contradion, the other 

 Parts are rendered quite opake : and in this 

 Space the Microfcope difcovers a Kind of 

 flud:uating Motion, very much like that in 

 the Arms, wherewith it feems to commu- 

 nicate. The outward Coat is white like the 

 Arms, and made up of minute Annuli or 

 Ringlets, that double in the midft, and can, 

 occafionally, be folded clofe together, in the 

 manner of a Paper Lanthorn. Thefe may 

 plainly be feen, when the Body is in its mid- 

 dle Degree of Extenfion: but when it is 

 quite ftretched out, they become unfolded, 

 and confequently not diftinguiihable ; and 

 when quite contracted, are not perceivable, 

 by their being brought too clofe. The Ap- 

 pearance of them may be underflood by 

 fome of the foregoing Draughts.--- See the 

 Figures, Fage 12 and 14. 



Such a Structure accounts, in fome meafure, 

 for that extraordinary Ability this Creature 

 has, of fo extending or contradting every 

 Part about it, that it is difficult, if not im- 

 poffible, to afcertain the real Length or 

 Thicknefs of any. It will eafily be conceived 

 that the Thicknefs muft increafe as the 

 Length diminifhes: for its Body is, probably, 

 compofed of longitudinal, and circular, or 

 perhaps fpiral Fibres, both capable of great 

 Extenfion or Contradion 5 and which coun- 

 tergdt, in fuch a Manner, that when one ex- 

 tends, 



