INTRODUCTORY. 15 



A.\GEI0L0G1. 



Study of vascular system, arteries, veins and lym- 

 phatics. 



Arteries. — They form two systems, the pulmonary 

 and .aortic. 



General form. — Dycotyledonic division, or two by 

 two. 



Form of arteries. — Kegularly c^dindrical in their 

 wliole length. 



Mode of origin. — Angular, or at right, acute or 

 obtuse angle. 



Situation. — Generally deeply situated. 



Direction. — Straight or fluxuous. 



Connections. — With veins, nerves, muscles, bones, 

 skin and cellular tissue, which form their sheatli of 

 envelopment. 



Anastomoses. — By convergence, arches or transverse 

 communications. 



Mode of distribution. — Terminal and collateral 

 brandies ; the terminal form the capillary subdivision. 



Structure. — They have tlu'ee coats, one internal 

 serous, one middle fibro-elastic, one external cellular ; 

 they receive nerves from the ganglionary or cerebro- 

 spinal axis, also blood-vessels forming the vasa vasorum. 

 They present some anomalies. 



