( 232 ) 



arteries into the veins, where they are united), as diflin^lly as any 

 perfoii can polTibly imagine. 



"When thefe Tadpoles were fomedays old, thofe dependent parts, 

 wherein the circulation of blood I have defcribed was performed, 

 were no longer to be ieen, being, as it fcemed to me, grown over by 

 the animal's Ikin. Isut I even then faw fomething of a rapid mo- 

 tion, as before defcribed, performed on each fide the head, though 

 I could not diftinguilh it to be the circulation of the blood ; at the 

 fame time, the head became fo conjoined to the body, that it 

 could not be dillinguiflied from it. 



The circulation of the blood, as seen in the tail of the Tadpole, 

 has been noticed in another place,* therefore no more need be added 

 here, than that my obfervations on this creature were not made upon 

 a fnigle infpection of the fubject ; but I often repeated the fame, on 

 account of the pleafure I took in the fight, and in different Tadpoles, 

 but I always found the appearance to be the fame. And one thing 

 is here worthy of not^, that in the very fmall veflels at the greateft 

 dhhmce from the heart, as in the extremity of the tail, there did not 

 appear fuch a foi'cible and vehement protrufion as in the veflels near 

 the heart ; but though the blood in thofe fmall veflels appeared to 

 move in an uninterrupted courfe, yet it could plainly be feon, that 

 at every pulfation of the heart the courfe was a little accelerated. 



I have in another place faid, that the particles or globules of blood, 

 from whence its rednefs proceeds, are fo minute that a million of 

 them taken together would not equal the fize of a large grain of land, 

 and from hence we may eafily conclude how exceffively fmall mult 

 be the vellels in which this circulation is performed. 



As many perfons have never feen a Tadpole, I have caufed a draw- 

 ing to be made of this creature, which, defpifed as it is, has afforded 

 me the greateft pleafure ; for the circulation of the blood, in this 

 animal, is more admirable to behold than in any other creature or 

 filh I ever faw : and luch has been my delight in viewing it, that 



* Vol. I. p. 92. 



