$41 Structure of the Blood Veffels. [Book IX, 



exceptions, which will be more particularly noticed in 

 ipeaking of the venous fyftem. The trunks of the 

 veins, and almoft all the arteries, are deeply feated i 

 but the fmaller veins are every where thickly diftri- 

 buted on the furface of the body, immediately below 

 the fkin. By this ftructure a paflage is provided for- 

 the blood on the furface of the body, where the in-? 

 ternal veins are fo comprefied by the aclion of rrmfcles 

 as not eafily to tranfmit their contents. The external 

 and internal veins communicate very freely, 



