C 54] 
fion, and their utmoft elaftic Expanfion> except 
chang’d into either State by Tome adventitious 
Caufe. 
XVI. 
Of the Circulation of the Blood in the minute 
Veffels . 
The Blood appears, by the Microfcope, to flow 
from Arteries into Veins immediately *, Which is 
ealily feen in the Webs of Frogs, Tails of Fifhes, 
My t lilt y and the like; and, I doubt not, would ap- 
pear fo in Mufcies, if they were thin enough to be- 
come tran (parent for Viewing with Glades. There- 
fore the Arteries and Veins may be confidered as 
continued Tubes, terminating in nothing ; but as the 
Arteries arife immediately from the Heart, fo they 
run to the Extremities of the Lungs and Body, rami- 
fying and decreafing in Diameter, till they become 
invifible to the naked Eye, and gradually become 
Veins, which unite into Trunks, increafmg in Dia- 
meter till they arrive at, and open into, the Heart 
again. So that Nutrition and the Secretions are car- 
ried on by minute Twigs, from thefe continued ca- 
pillary Canals + fent off to the Glands, and to the 
Parts to be nourifhed. ^ 
XVII. 
* Wirbouf the Intervention of any Veiicles, fuel: as Mayow fug- 
gefted. See Tab I. Fig. 3. 
•-j- Where the Arteries degenerate into Veins. 
3 
