HARVEY. 91 



ficial veins show themselves tumid and knotted, the pulse 

 at the wrist in the same instant beginning to beat as 

 it did before the application of the bandage. The tight 

 bandage not only compresses the veins, but the arteries 

 also, so that blood cannot flow through either. The 

 slacker ligature obstructs the veins only, for the arteries 

 lie deeper and have firmer coats. " Seeing, then," says 

 Harvey, " that the moderately tight ligature renders the 

 veins turgid, and the whole hand full of blood, I ask, 

 Whence is this ? Does the blood accumulate below the 

 ligature coming through the veins, or through the 

 arteries, or passing by certain secret pores ? Through 

 the veins it cannot come ; still less can it come by any 

 system of invisible pores ; it must needs, then, arrive by 

 the arteries." 



The third position to be proved is that the veins 

 return the blood to the heart from all parts of the body. 

 That such is the case might be inferred from the 

 presence and disposition of the valves in the veins ; for 

 the office of the valves is by no means explained by the 

 theory that they are to hinder the blood from flowing 

 into inferior parts by gravitation, since the valves do not 

 always look upwards, but always towards the trunks of 

 the veins, invariably towards the seat of the heart. The 

 action of the valves is then demonstrated experimentally 

 on the arm bound as for blood-letting. The point 

 of a finger being kept on a vein, the blood from 



