same or a different kind, and separate it from the Nerve of the Eighth pair, and lay it bare above an inch. Then make a strong Ligature on the upper part of the Arterie, not to be untied again: but an inch below, videl. towards the Heart, make another Ligature of a running knot, which may be loosen'd or fastned as there shall be occasion. Having made these two knots, draw two threds under the Artery between the Ligatures; and then open the Artery, and put in a Quil, and tie the Artery upon the Quill very fast by those two threds, and stop the Quill with a stick. After this, make bare the Jugular Vein in the other Dog about an inch and a half long; and at each end make a Ligature with a running knot, and in the space betwixt the two running knots drawn under the Vein two threds, as in the other: then make an Incision in the Vein, and put into it two Quills, one into the descendent part of the Vein, to receive the bloud from the other Dog and carry it to the Heart; and the other Quill put into the other part of the Jugular Vein, which comes from the Head (out of which, the second Dogs own bloud must run into Dishes.) These two Quills being put in and tied fast, stop them with a stick, till there be occasion to open them.
All things being thus prepar'd, the Dogs on their sides towards one another so conveniently, that the Quill may go into each other, (for the Dogs necks cannot be brought so near, but that you must put two or three several Quills more into the first two, to convey the bloud from one to another.) After that unstop the Quill that goes down into the first Dog's Jugular Vein, and the other Quill coming out of the other Dog's Artery; and by the help of two or three other Quills, put into each other, according as there shall be occasion, insert them into one another. Then flip the running knots, and immediatly the bloud runs through the Quills, as through an Artery, very impetuosly. And immediately, as the bloud runs into the Dog, unstop the other Quill, coming out of the upper part of his Jugular Vein (a Ligature being first made about his Neck, or else his other Jugular Vein being compress'd by ones Finger;) and let his own bloud run out at the same time into Dishes (yet not constantly, but according as you perceive him able to bear it)
till the other Dog begin to cry, and faint, and fall into Convulsions, and at last dye by his side.
Then take out both the Quills out of the Dogs Jugular Vein, and tye the running knot fast, and cut the Vein asunder, (which you may doe without any harm to the Dog, one Jugular Vein being sufficient to convey all the bloud from the Head and upper parts, by reason of a large Anatomosis, whereby both the Jugular Veins meet about the Larinx.) This done, sow up the skin and dis-miss him, and the Dog will leap from the Table and shake himself and run away, as if nothing ailed him.
And this I have tryed several times, before several in the Universities, but never yet upon more than one Dog at a time, for want of leisure, and convenient supplyes of several Dogs at once. But when I return, I doubt not but to give you a fuller account, not only by bleeding several Dogs into one, but several other creatures into one another, as you did propose to me, before you left Oxford; which will be very easie to perform; and will afford many pleasant and perhaps not unuseful Experiments.
But because there are many Circumstances necessary to be observ'd in the performing of this Experiment, and that you may better direct any one to doe it, without any danger of killing the other Dog, that is to receive the others bloud, I will mention two or three.
First, that you fasten the Dogs at such a convenient distance, that the Vein nor Artery be not stretched; for then, being contracted, they will not admit or convey so much bloud.
Secondly, that you constantly observe the Pulse beyond the Quill in the Dogs Jugular Vein (which it acquires from the impulse of the Arterious bloud:) For if that fails, then 'tis a sign the Quil is stopt by some congealed bloud, so that you must draw out the Arterial Quill from the other, and with a Probe open the passage again in both of them, that the bloud may have its free course again. For, this must be expected, when the Dog, that bleeds into the other, hath lost much bloud, his heart will beat very faintly, and then the impulse
of bloud being weaker, it will be apt to congeal the sooner, so that at the latter end of the work you must draw out the Quill ofter, and clear the passage; if the Dog be faint-hearted, as many are, though some stout fierce Dogs will bleed freely and uninterruptedly, till they are convuls'd and dye. But to prevent this trouble, and make the experiment certain, you must bleed a great Dog into a little one, or a Mastive into a Curr, as I once try'd, and the little Dog bled out at least double the quantity of his own bloud, and left the Mastive dead upon the Table, and after he was untyed, he ran away and shak'd himself, as if he had been only thrown into water. Or else you may get three or four several Dogs prepared in the same manner; and when one begins to fail and leave off bleeding, administer another, and I am confident one Dog will receive all their bloud, (and perhaps more) as long as it runs freely, till they are left almost dead by turns: provided that you let out the bloud proportionably, as you let it goe into the Dog, that is to live.
Thirdly, I suppose the Dog that is to bleed out into dishes will endure it the better, if the Dogs that are to be administred to supply his bloud, be of near an equal age, and fed alike the day before, that both their blouds may be of a neer strength and temper.