PART VIII. 



GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 

 CHAPTER VII. 



OF THE BLOOD-VESSELS IN GENERAL. GENERAL ANATOMY OF THE ARTE- 

 RIAL SYSTEM. GENERAL REMARKS UPON THE HEART. GENERAL ANAT- 

 OMY OF THE VENOUS SYSTEM. 



Of the Blood-vessels in General. 



THE blood-vessels are flexible tubes, of a peculiar texture, 

 through which blood passes from the heart to the different parts 

 of the body, and returns again from these parts to the heart. 

 They are to be found, in varying proportions, in almost every 

 part of the body, and seem to enter into its texture. 



The tubes which carry blood from the heart, are more sub- 

 stantial and more elastic than those through which it returns to 

 the heart. They are generally found empty after death ; and, 

 therefore, were called Arteries by the ancient anatomists, who 

 supposed that they carried air, and not blood. 



The tubes which return the blood to the heart are denomi- 

 nated Veins. They are less substantial and less elastic than 

 arteries, and are generally full of blood in the dead subject. 



There are two great arteries, from which all the other arterial 

 vessels of the body are derived. They are very justly compar- 

 ed to the trunks of trees, and the smaller vessels to their 

 branches. One of these great arteries, called the Aorta, carries 

 blood to every part of the body. The other great vessel, 

 called the Pulmonary Artery, carries blood exclusively to the 

 lungs. 



The veins which correspond to the branches of the Aorta, 

 unite to each other, so as to form the two great trunks that 

 proceed to the heart. One of these trunks, coming from the 



