60 ON THE KOTION OF THE BLOOD. 



SECT. VII. 



ON THE MOTION OF THE BLOOD. 



84. The blood, to whose great and multifarious im- 

 portance in the system we have slightly alluded, (16) 

 is conveyed, with a few exceptions, (5) into the most 

 internal and extreme recesses. This is proved by the 

 minute injection of the vessels, and by the well known 

 fact of blood issuing from almost every part on the 

 slightest scratch. 



85. This purple fluid does not, like an Euripus, ebb 

 and flow in the same parts, as the ancients imagined, 

 but pursues a circular course ; so that being propelled 

 from the heart into the arteries, it is distributed through- 

 out the body, and returns again to the heart through 

 the veins. * 



86. We shall, therefore, say something at present 

 of the vessels which contain the blood ; and afterwards, 

 of the powers by which they propel and receive it. 



87. The vessels which receive the blood from the 

 heart and distribute it throughout the body, are termed 

 arteries. These are upon the whole less capacious than 



• Among warm-blooded animals, the egg, especially at the fourth and fifth day 

 of incubation, if placed under a simple microscope, such as the Lyonetian, is 

 most proper to demonstrate the circulation. 



Among frogs, the most proper is the cquuleus of Licbcrkuhn, derribed in 

 the Mem. dt FActd. dt Btrlim. 1745. 



