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In other places, and alfo in the two fins D E and L M, I faw the 

 blood not only running along, but alfo taking its \\'hole courfe for- 

 ward and back again, in manner before defcribed. 



Now, if in the tail of fo fmall a fifli, as this which is pictured at 

 fg. 4, there are to be found thirty-four diftinft circulations of blood, 

 what an incredible number of them mud there be in an human body ! 

 And this being fo, it is no wonder, that, upon the lead pun6lure made 

 by a needle, or any other fmail inftrument, the blood illiies forth. In- 

 deed, from thefe my obfervations, I am well afliired, that, in the 

 fpace of a finger's nail, in any part of the furface of our bodies, there 

 are more than a thouland circulations of blood. 



Some years after thefe, and other obfervations of the like kind, liad 

 been made by miC, I accidentally fell into converfation with a certain 

 learned Gentleman, (not a native of Holland) on this fubje^l of the 

 circulation of the blood, particularly in the minuteft veflels which are 

 contained in a very I'mall fpace, and that this circulation could as 

 plainly be feen, as with tiie naked eye we fee water fpringing up 

 from a fountain, and falling down again ; but though I ufcd all my 

 endeavours to convince him of the truth of what I advanced, yet 

 this learned Gentleman refufed to give credit to my words, declar- 

 ing that he could not form any conception of the matters which I 

 related. 



This Gentleman's incredulity took up much of my tlioughts, par- 

 ticularly upon a time when I had got Ibme very fmall eels, not 

 longer than one's little finger : and on this occafion I fcnt for a 

 limner, who I knew was a very curious obferver, and had a very 

 acute fight, judging that he would be able to make a drawing of fome 

 of thofe blood -vefleLs. 



I then put one of thefe fmall eels into a glafs tube, about the fize 

 of a goofe-quill, and placing it before the microfcope, I delivered it 

 into the limner's hands, defiring him particularly to attend to the 

 current of blood which at that time was moft dirtin6liy to be feen in 



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