( 603 ) 
thirdly, It reemed difficult (ro meat Icaft) to folve this Intefti- 
nalcontraftion, though thefe lateral apertures were fuppofed: 
For, if fibres (whether confidered as fingle, or as conftituving a 
raufcle) be contracted according to ihcir length from fonie influ- 
ent matter,it muft be(2ccording to my fence) from a diftenfion of 
them in breadth ; and, in order to that, this matter mu ft undergo 
fome confinement in the part to bediftended ; but if they have la- 
teral perforations (and thofe in the oppofite part proportionate 
to thofe in that which admits this matter, which muft^ I conceive, 
begranted,fincc the contraftion is all along thelnteftines propor- 
tionate,) how can it be fuppofed, a diftenfion ( at leaft fuch a one as 
is here required ) can happen, when the matter defigned to efFeft it 
has fo ready a paflage forth, erpecially its determination from the 
impelling caufe being in right lines downward ? If it were objefi- 
ed, that the motion of this fubfl-ance might be fuppofed to be la- 
teral as well as dir eft, in regard there would bea paffage for it in- 
to the fibres as well as through the Anaftomofes, and that in pro- 
portion larger than through thefe, whence nothing feems to hin- 
der but that a diftenfion of them might follow; I fuppofed, it 
might be replyed, that, by reafonof fuch a diftorfion of part of 
the impelled matter, it feem3,thac the imprefTed morion would be 
foon loft (according to the laws of morion) unlefs the impelling 
caufe were more violent than I fee reafon in this cafe to imagine it: 
to be. But indeed I think^no Anatomifts have obferved,that muf- 
cles ( fuppofing thefe fuch j receive their aftuating matter in at 
their fides, or,when their motion ceafes,fend it forth that way;bu£ 
all, fp far as has been obferved, are fenced with a confider ly 
compaft, and (comparatively) impervious membrane. 
Fourthly^ I confidered, that all mufcles are obferved to have 
two tendons, one at each extremity, by the approach of one 
whereof toward the other, its motion, which is contraflion, is 
performed ; but it feems hard to conceive, that thefe tendons 
fliould coincide fas in this fuppofition they muftj and,if they do, 
I prefumed it would be difficult to determine, what pare of thefe 
•circular mufcles (if fuch) the tendons are,and where the motion 
fliould begin in each;it being obferved,that all mufcles arefaftned 
tofome, either fim ply or comparatively, unmovable part,toward 
which (ordinarily) they move, and by which the inftinft ofmoti- 
.on is from the nerves conveyed to them : But no Anatomifts, (fo 
far as I had obferved ) having difcovered, that any one part of 
thefs- 
