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In my feveral obfen/ations on the circulation of the blood in tiflies 

 I have not been able clearly to latisfy myfelf with regard to the 

 fliape of the globules or component particles of the blood, for they 

 fomctimes appeared of a fpherical, and fometimes of an oval and 

 even a flat lliape, and fometimes an irregular figure ; this I fome- 

 times attributed to my glafles not being of fufficient magnifying 

 power to dilHnguifh them, and fometimes- to the pofltion in which 

 they appeared to the eye, for, while in circulation, they tumbled one 

 over another, fometimes prefenting one part and fometimes another 

 to the view; and I alfo thought that it might be owing to the llrait- 

 nefs of the vefl^els, in which the particles of blood, being of a yield- 

 ing nature, might, by the comprelFion, lofe their fpherical figure. 



In order to fatisfy myfelf in fome degree on this head, I cut olT 

 pieces from the tails of feveral fmall flat fifli, fuch as Plaice and 

 Flounders, in order to view the blood when drawn out of the vefl^els, 

 and the rather, becaufe I could not perfuade myfelf, that the na- 

 tural fliape of the particles of blood in fifties was an oval ; foraf- 

 much, as a fpherical feemed to me to be the more perfe6l form. 

 For I was of opinion, that the particles of blood in fifties were coni- 

 pofed of fix globules, in like manner with the blood in man, and in 

 terreftrial animals : and I feveral times faw the particles of fifties 

 blood, the original texture of which was broken, and in which I 

 could difl:in6lly fee four or five, and in fome few of them fix com- 

 ponent particles. I, however, thought it worthy of note, that many 

 of thefe particles of blood appeared to me of an oval fliape, fome 

 few others roundilh, and others of a perfe6l fpherical figure. 



In order farther to profecute my inquiries on this fubjeft, I took 

 the blood of a Salmon not quite dead, which was received into a 

 glafs tube, about the fize of a fmall writing pen : this blood, after a 

 fliort time, became coagulated ; but having reftored it in part to its 

 fluidity, I put it into a fmaller glafs tube, in which I viewed it, hold- 

 ing it fo, that the particles of blood might be kept in motion con- 

 tinually, by which means many of the particles appeared before my 



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