CIRCULATION OF THE BLOOD 121 



Now is not this the cause of all tumefaction, as indeed 

 Avicenna has it, and of all oppressive redundancy in parts, 

 that the access to them is open, but the egress from them is 

 closed? Whence it comes that they are gorged and tume- 

 fied. And may not the same thing happen in local inflamma- 

 tions, where, so long as the swelling is on the increase, and 

 has not reached its extreme term, a full pulse is felt in the 

 part, especially when the disease is of the more acute kind, 

 and the swelling usually takes place most rapidly. But these 

 are matters for after discussion. Or does this, which occurred 

 in my own case, happen from the same cause? Thrown 

 from a carriage upon one occasion, I struck my forehead 

 a blow upon the place where a twig of the artery advances 

 from the temple, and immediately, within the time in which 

 twenty beats could have been made I felt a tumour the size 

 of an egg developed, without either heat or any great pain : 

 the near vicinity of the artery had caused the blood to be 

 effused into the bruised part with unusual force and velocity. 



And now, too, we understand why in phlebotomy we apply 

 our ligature above the part that is punctured, not below it; 

 did the flow come from above, not from below, the constric- 

 tion in this case would not only be of no service, but would 

 prove a positive hindrance; it would have to be applied 

 below the orifice, in order to have the flow more free, did the 

 blood descend by the veins from superior to inferior parts; 

 but as it is elsewhere forced through the extreme arteries 

 into the extreme veins, and the return in these last is 

 opposed by the ligature, so do they fill and swell, and being 

 thus filled and distended, they are made capable of projecting 

 their charge with force, and to a distance, when any one of 

 them is suddenly punctured ; but the ligature being slackened, 

 and the returning channels thus left open, the blood forth- 

 with no longer escapes, save by drops ; and, as all the world 

 knows, if in performing phlebotomy the bandage be either 

 slackened too much or the limb be bound too tightly, the 

 blood escapes without force, because in the one case the 

 returning channels are not adequately obstructed; in the 

 other the channels of influx, the arteries, are impeded. 



