OP THE VASCULAR SYSTEM. 237 



CHAPTER IV. 



OP THE VASCULAR SYSTEM. 



346. The vascular system, syslema vasorum, results from 

 the union of a multitude of ramified canals, communicating 

 with each other, and in which the nutritive fluids continually 

 circulate throughout the whole body; receiving at the tegu- 

 mentary sur&ces the substances of extrinsic absorption, and 

 there yielding those of the excreting secretion; alternately 

 depositing in and taking from the close cavities of the serous 

 membranes, and the areolae of the cellular tissue, continually 

 furnishing the substance of the organs with materials of com- 

 position, and constantly conveying away those of decompo- 

 sition. 



347. In the simplest animals, the whole mass of the body, 

 every way equally permeable, is directly imbibed with the 

 matters of absorption, and throws out in as simple a manner 

 those of excretion; in animals placed a little higher in the 

 scale of organization, the tegument, the essential seat of ab- 

 sorption and extrinsic secretion, is more or less ramified in 

 the mass of the body, by means of which the substances for 

 absorption are distributed, and those of excretion drawn from, 

 the diverse parts of the jnass of the body; finally in those of 

 a still higher degree, and which embraces a great part of the 

 animal kingdom, we observe vessels penetrating the mass of 

 the body and ramified in every direction, every way distri- 

 buting and taking up again the matter destined for nutrition. 



348. In man, as well as in many other animals, the blood 

 contained in the vessels, is continually conveyed from a cen- 

 tral point to every part, and returned from all parts to the 

 centre, so as to describe a circle; hence to this vascular system 



