HEART AND BLOOD. 57 



the fillet, swell, and become dilated, whilst the arteries shrink; 

 and such is the degree of distension of the veins here, that it is 

 only very strong pressure that will force the blood beyond the 

 fillet, and cause any of the veins in the upper part of the arm 

 to rise. 



From these facts it is easy for every careful observer to learn 

 that the blood enters an extremity by the arteries ; for when 

 they are effectually compressed nothing is drawn to the mem- 

 ber ; the hand preserves its colour ; nothing flows into it, neither 

 is it distended; but when the pressure is diminished, as it is 

 with the bleeding fillet, it is manifest that the blood is instantly 

 thrown in with force, for then the hand begins to swell ; which 

 is as much as to say, that when the arteries pulsate the blood 

 is flowing through them, as it is when the moderately tight liga- 

 ture is applied; but where they do not pulsate, as, when a 

 tight ligature is used, they cease from transmitting anything; 

 they are only distended above the part where the ligature is 

 applied. The veins again being compressed, nothing can flow 

 through them ; the certain indication of which is, that below 

 the ligature they are much more tumid than above it, and than 

 they usually appear when there is no bandage upon the arm. 



It therefore plainly appears that the ligature prevents the 

 return of the blood through the veins to the parts above it, and 

 maintains those beneath it in a state of permanent distension. 

 But the arteries, in spite of its pressure, and under the force 

 and impulse of the heart, send on the blood from the internal 

 parts of the body to the parts beyond the bandage. And herein 

 consists the difference between the tight and the medium 

 bandage, that the former not only prevents the passage of the 

 blood in the veins, but in the arteries also ; the latter, how- 

 ever, whilst it does not prevent the pulsific force from extend- 

 ing beyond it, and so propelling the blood to the extremities of 

 the body, compresses the veins, and greatly or altogether im- 

 pedes the return of the blood through them. 



Seeing, therefore, 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 arrive by the 



