136 Circulation of the Blood 



of those who as'sert their belief that the part below the 

 tube does not pulsate when the ligature is tied, may be 

 made the more apparent, I can state, after having made 

 the trial, that the inferior part will continue to pulsate 

 if the experiment be properly performed ; and whilst 

 they say that when you have undone the ligature the 

 inferior arteries begin again to pulsate, I maintain that 

 the part below beats less forcibly when the ligature is 

 untied than it did when the thread was still tight. But 

 the effusion of blood from the wound confuses every- 

 thing, and renders the whole experiment unsatisfactory 

 and nugatory, so that nothing certain can be shown, 

 by reason, as I have said, of the hemorrhage. But if, 

 as I know by experience, you lay bare an artery, and 

 control the divided portion by the pressure of your 

 fingers, you may try many things at pleasure by which 

 the truth will be made to appear. In the first place, 

 you will feel the blood coming down in the artery at 

 each pulsation, and visibly dilating the vessel. You 

 may also at will suffer the blood to escape, by relaxing 

 the pressure, and leaving a small outlet ; and you will 

 see that it jets out with each stroke, with each con- 

 traction of the heart, and with each dilatation of the 

 artery, as I have said in speaking of arteriotomy, and 

 the experiment of perforating the heart. And if you 

 suffer the efflux to go on uninterruptedly, either from 

 the simple divided artery or from a tube inserted into 

 it, you will be able to perceive by the sight, and if you 

 apply your hand, by the touch likewise, every character 

 of the stroke of the heart in the jet ; the rhythm, order, 

 intermission, force, &c., of its pulsations, all becoming 

 sensible there, no otherwise than would the jets from a 

 syringe, pushed in succession and with different degrees 

 of force, received upon the palm of the hand, be obvious 

 to sight and touch. I have occasionally observed the 

 jet from a divided carotid artery to be so forcible, that, 

 when received on the hand, the blood rebounded to 

 the distance of four or five feet. 



