( 1^3 ) 



In the tail of this tadpole, I obferved a vellel, of a fize to admit 

 twenty of the particles or globules at once ; fo that this was a large 

 veilel, in proportion to thole which I have before defcribed. A fmall 

 part of it is reprefented 3-tJig. 9, L M ; and from tliis, proceeded a 

 minute veflel, which is fliewn at M O. 



The current in this veflel, from L to M, was not ib fwift as I ob- 

 ierved in the other veffels, and for this reafon, that, in another part 

 of it, at R, the blood was coagulated, infomuch, that no diftinft par- 

 ticles could be perceived in it, but only an uniform rednefs ; but in 

 the fniall vellel N, the current was as fwift as in any of the others. 



In confequence of this flagnation at R, the blood was driven for- 

 wards from M to P, with every pulfation of the heart, and inftantly 

 ran back again, in like manner, as if with the naked eye Me beheld 

 a fwift alternate or reciprocal motion, like that of a faw. 



\Ye know, that water cannot be compreffed into a lefs fpace than 

 it naturally occupies ; and this being alfo the cafe with regard to the 

 blqod, -we muft conclude, that the coat of this veflel, between N and 

 P, and alfo a little below N, was, at every pulfation, expanded in 

 diameter, and, at the intermitting of the pulfation, would contra6t 

 itfelf, and fo drive the blood back ao;ain. 



Keeping my eye fixed on the obje6l, I perceived, in a little time, 

 the blood between P and R begin to move, and by little and little, 

 from P toM ards R, to have the fame alternate motion to and fro, as 

 I have before defcribed. At the fame time, the blood in the veflel 

 N S, where, at firft, little or no motion could be feen, the current 

 \vas nov/ as fwift as ufual. And in the fmall blood-veflel, marked 

 V O, which was only of a fize to admit one globule at a time, and 

 wherein I could not at firft difcover any motion, the circulation was 

 now reftored ; but the particles of blood were few in number, and at 

 a diftance from each other. 



