On Frogs, and the manner in which their young are produced from 

 Tadpoles, tvith the circulation of the blood Jeen in them : alfo 

 on thefliape of the component particles of the blood. 



W E have two forts of Frogs in this country, one which ufed to 

 be found in great numbers about the town of Delft, but of late 

 years only few of them have been feen, by reafon, as I believe, 

 that their fpawn has been devoured by a fmall kind of filh ; and I 

 have fometimes feen this (pawn in the fmall ditches which divide 

 our fields, lying in fuch quantities, that the furface of the water 

 feemed almoft covered with it. The other fpecies of Frogs is much 

 fewer in number, but of a larger fize, and they leap farther than 

 the others, and the hind parts of their bodies, or rather the thickefl 

 parts of their legs, are ufed by the French, as good food. Refpe6l- 

 ing the propagation of thefe laft, as a particular fpecies, I was for 

 fome time in doubt, not having obferved them couple together, nor 

 feen any of their eggs or fpawn. 



But one day, at the end of the month of May, walking in a mea- 

 dow for my recreation, and not thinking of this fubjedl, becaufe the 

 time of the other fort of Frogs laying their eggs was long pall, my 

 attention was excited by the noife or croaking, which thefe iall 

 mentioned Frogs make both by day and night, in hot weather, 

 whereupon I went to the fide of the water, and I thought that I 

 faw fome of their eggs adhering to a green leaf in the water, and i'o 

 in fa6l it proved. Thefe eggs are not fo ealily to be difcerned, as 

 thofe of the common Frogs, becaufe the glutinous matter or jelly 

 which contains them, fwims deeper in the water, and is alfo lefs 

 in quantity, 



Ff 2 



