that means their Di^^^/^?;?/ are exceedingly contrafted. In 
conformity to this condition of the Bronchi the Vnlmonary 
Artery and Veia muft likewife, either by means of their 
Mufcular Coits contrad themfelves to the C^mc Dime?tfio^s^ 
or lye in Folds or Corrngations^ which is lefs probable. 
On the other hand, when the Ribs are elevated, and the, 
Di^2/)^r^^/!;r^ bears downward, the Airrudiing into the Lungs, 
flioots out the Carti'lagwous Pvings, and Divaricates the 
Branches of the Trachea^ and by chem extends and divari- 
cates the fcveral divifions of the Fdmomry Artery and 
Veins, and thereby lengthens and enlarges their Cavities. 
This enlargement of their Cavities k very confiderable, 
not only upon the fcore of the addidonj v/hich they re- 
ceive in length thereby, but alfo upon the account of their 
Divaricatiofi» For whereas, when the Ribs are depreft, 
and the Lungs fabfide, the Blood Veffels are not only con- 
traded, ( as I have already obferv'd ) but their Branches, 
vii^hich are exceeding numerous, approaGh one another, and- 
lie in juxta-polition, by which their Cavities are very much 
comprefs'd and ftreighten'd : when, the Ribs are elevated^ 
and the Lungs turgid with Air, not only the Fibres, by 
which their Coats in the oppofite . State were contraded, 
are extended, but thofe innumerable Veffels, which lying 
befpre in linesaimofl: parallel upon one another, comprefs'd 
one another, making an acute Angle .at their Jundures, are 
divaricated and feparated from each other, and make aa 
obiufi^ whereby their Channels are widen'd. 
Thus a paiTage is opened to the Blood, from the Righ 
Ventricle of the Heart to the If//, thro the Lungs, to which 
it cou d not other wife pais ^ and the oppofition, which the 
Blood, contained in that Ventricle, mult otherwife neceflkr- 
rily have made to its conftridion, is taken ox% and the Sy 
jlolc thereby facilitated. 
Nor is that all. For the Dlaftok being caus'd (as 1 (hall 
in the feqael (hew) by the Force of the Blood ruihingjnto 
- the Ventricles, this Ampiiation and Extenfioaof the P///» 
