find the fame pradis'd m this Operation, the old and corrupt 
being firft cvacuateuj to make room for new and pure. And 
thofe alfo that decry bleeding, as that which too much weak- 
ens the fick, willhavenoreafon to complain 5 fince the new 
blood conduceth to ftrengthen them more. 
Laftly, Every one knows that many perfons dye through 
lofs of blood, and Hsemorrhagies not to be ftopt, many are 
eraacerated by them^ and others precipitated into untimely 
old Age, by defed: of blood and vital heat. Now who 
doubts but the Tr^«j/«/<?w of a mild and laudable blood may 
prefer ve the one, and prolong the life of the others. A man 
may forefce fome benefits and advantages from this Operati« 
on in Pleuri(ies^ the fmall Pox^ Leprojies^ Cancers^ Vlcers ^ St^ 
Anthonies fire^ Madmfs^ Dotage ^ and other Maladies arifing 
from the Malignity of the blood ; But the fuccefs is rather 
to be expefted in Experiments, which will be made within a 
little time. In the interim, give me leayc to acquaint you 
with my Judgment concerning the Eleftion of the Animal 
that is to communicate its blood. 
: Many have conceived, That if ever the ^ramfujion oi blood 
fliould come to be praftis'd upon men , it ought to be done 
:with blood of the fame Species i and confequently. That it 
would be a very barbarous Operation, to prolong the life of 
fome, by abridging that of others. But for my part , I am 
far from that Opinion,and I am perfwaded that it will be much 
more expedient to make ufe of the blood of other Animals, 
than of that of men, for many reafonsj the chief whereof are 
thefe. 
I. 'Tis eafie enough to judge, That the blood of Animals 
islefsfuUof impurities, than that of raen^ becaufe debauch^ 
ednefs and irregularity in eating and drinking, are fo ordina- 
ry CO them, as to us. Sadnefs, Envy,Anger, Melancholy, Dif- 
quiet, and generally all the Paffions , are as fo many caufes 
which trouble the life of man, and corrupt the whole fub- 
ftance of the blood : Whereas the life of Brutes is much more 
regular, and lefs fubjedt to all thofe miferies, which we ought 
to confider as fad confequences of the prevarication of our 
firftParents» And indeed Experience fufEcieqtly (liews us, 
Ddd2 That 
