There are many things I have observed upon bleeding Dogs to death, which I have seen since your departure from Oxford, whereof I shall give you a relation hereafter; in the mean time since you were pleased to mention it to the Royal Society, with a promise to give them an account of this experiment, I could not but take the first opportunity to clear you from that obligation, &c.
So far this Letter; the prescriptions whereof having been carefully observ'd by those who were imployed to make the Experiment, have hitherto been attended with good success; and that not only upon Animals of the same Species (as two Dogs first, and then two Sheep) but also upon some of very differing Species (as a Sheep and a Dog; the former Emitting, the other Receiving)
Note only, that instead of a Quill, a small crooked thin
Pipe of Silver or Brass, so slender that the one end may enter into a Quill, and having at the other end, that is to enter into the Vein and Arterie, a small knob, for the better fastening them to it with a thread, will be much fitter than a strait Pipe or Quill, for this Operation: for so they are much more easie to be managed.
'Tis intended, that these tryals shall be prosecuted to the utmost variety the subject will bear: As by exchanging the bloud of Old and Young, Sick and Healthy, Hot and Cold, Fierce and Fearful, Lame and Wild Animals, &c., and, that not only the same, but also of differing kinds. For which end, and to improve this noble Experiment, either for knowledge, or use, or both, some Ingenious men have already proposed considerable tryals and Inquiries; of which perhaps an account will be given hereafter. For the present we shall only subjoyn some.
Considerations about this kind of Experiments.
1. It may be consider'd in them, that the bloud of the Emittent Animal, may after a few minuts of time, by its circulation, mix and run out with that of the Recipient. Wherefore to be assured in these Tryals, that all the bloud of the Recipient is run out, and none left in him but the adventitious bloud of the Emittent, two or three or more Animals (which was also hinted in the method above) may be prepared and administred, to bleed them all out into one.
2. It seems not irrational to guess afore hand, that the exchange of bloud will not alter the nature or disposition of the Animals, upon which it shall be practised; though it may be thought worth while for satisfaction and certainty, to determine that point by Experiments. The case of exchanging the bloud of Animals seems not like that of Graffing, where the Cyons turns the Sap of the Stock, graffed upon, into its nature; the Fibres of the Cyons so straining the juice, which passes from the stem to it, as thereby to change it into that of the Cyons, whereas in this transfusion there seems to be no such
Percolation of the bloud of Animals, whereby that of the one should be changed into the nature of the other.
3. The most probable use of this Experiment may be conjectured to be that one Animal may live with the bloud of another; and consequently, that those Animals, that want bloud, or have corrupt bloud, may be supplyed from other with a sufficient quantity, and of such as is good, provided the Transfusion be often repeated, by reason of the quick expence that is made of the bloud.