J80 PHILOSOPHICAL TRANSACTIONS. [aNNO I7OO. 



the centre, made the one side of the round particle heavier, which hindered the 

 motion. 



When I perceived that the great number of round particles in the great glass, 

 mixed with a great number of animalcules, were gone in 3 days time, I con- 

 sidered whether these particles were not created as food for these animalcules. 

 Now when we see that the globules before-mentioned do not proceed from 

 themselves but by procreation, as we know that all plants and seeds are pro- 

 created, each seed though ever so small having its plant inclosed within it ; we 

 are now more than ever assured of the procreation of all things. As for me I 

 set it down as a certain truth, that the small round particles, found in the great 

 ones, are seeds, and that without them the round particles could not be produced. 



I caught a small frog, which I judged had been an egg the preceding spring, 

 and putting it into a glass tube, an inch wide and 10 inches long, I stopped 

 both the ends up with cork, yet in such a manner, that at one end the air had 

 free admission. I here viewed the toes of the fore-legs with a magnifying- 

 glass. to observe the circulation of the blood, which I could not discern without 

 great difficulty. But when I came to view the hindermost legs, I saw for se- 

 veral days successively, on the web-skins between the toes, the blood circulate 

 in several very small vessels, I also observed that when the frog stretched out 

 its leg, the circulation of the blood was thereby stopped for a little time, but as 

 soon as it stood still, the blood began to circulate again. After the frog had 

 been about 24 hours in the tube, I saw its excrements, as it were on a heap. 

 After it had been there 48 hours, it had fouled again ; and looking on the ex- 

 crements with a magnifying-glass, in the first excrement I saw that it had fed 

 upon an animal, whose body was beset with hair of several thicknesses, very 

 sharp pointed, which I judged to be of some flying insect ; when I viewed the 

 second excrement, I saw no hair, at first ; but upon laying it asunder, I saw 

 not only some hair, but also a piece of the foot, part of the eye, a piece of a 

 wing, and many pieces of the skin of an animal, whicli I judged to have been 

 a small insect, whose wings are covered with a sheath, very like those called 

 beetles. These excrements lay in a clear moisture round about them, 

 wherein swam or crept some eels, or about 30 small worms, the fore and 

 hinder-parts of whose body were very clear. 



These eels in the frog's excrement, are very like those found in vinegar, 

 if not altogether the same ; only with this difference, that the eels of the 

 vinegar, as they come out of the mother, are somewhat thinner and harder. 



In the first excrement I discovered only 2 of these eels. When I looked the 

 next day, and saw that the moisture wherein the small eels swam, was partly eva- 

 porated, and that the eels moved but very little, I put a little rain water round 



