we could conceive they were the Authors of their own 
motion, by receding every ways from the Center? of the 
Heart, inftead of contra£ting this, maftlneGeffarily en- 
large its bulk. Some other force muft be affigned, from 
which that proceeds. No more can the Fibres of the 
Heart effeft a Coiqtra^iiion by their Springinefs, for then 
the feveral partsof theHeart maft' be unequally moved» • 
Again^ if the heart were onct- dilated^ and their ela- 
fticl^ power over-balanced, by what means can they re- 
cover it. 
Tiie next doubt; is whether there be any exteriour 
Body^ which^ may ct)aap^e& the Fibres and evacuate 
the Ventricles. As fibr the external Bremen ts 5 the 
Liquor of the Pericardium^ is too inconfiderable a force 
to projed the blood to the extreme parts with fuch aa? 
Impetus^ as is necefTary to continue the Circulation* 
Nor can the Per'kardmm do tki^^^^ which if the Thorax 
be opened, does fuffer no vifible contraftlon^ notwith- 
ftanding the heart continiies to beat: Nor the Lungs,, 
for then the Contraftion could only be in Infpiration, . 
and the Perieardmm muft be preft on all fides clofe to * 
the H^rt, feth wMch are contrary to Experience* 
From the enumeration of thefe feveral ways it ap- 
pears, the DeCurtation of the Fibres of the Heart can * 
only proceed from a fubftance in their Pore and |Inter- 
ftices, which, fince no folid wedges are to be found ^ 
there, muft needs be a fluid Matter. 
But whence (hall this fluid be farniflied > i. Not : 
from the Liquor of the Pericardinm,^ fince in diffefting 
dead Bodies, this is found to be wanting ^ and if it be 
let out by dividing this Bag in a Dog, and the Heart 
be drawn through the Orifice, it continues not with* 
ftanding to beat. Befides, if the Fibres of the Heart 
were contrafted by imbibing the Serofities in the fame- 
manner as Ropes are^ this could not be dona under a 
Ions 
