VOL. XIX.J PHILOSOPHICAL TRANSACTION'S. gS 



ditch, and were busy in taking up some green herbs, to find small eels among 

 them, I desired them to bring me a pot full of the smallest of them to my 

 house, which they did accordingly, that I might search them very narrowly, to 

 try whether I could see any more concerning the circulation of the blood than 

 I had discovered before in greater ones. These were from 2-^ to 5 inches in 

 length. I put several of the least sort into my small tube, partly filled with 

 water, so that they could but just go into it. When I placed these small eels 

 before the glass, and fixed my eye on the fin near the tail, I saw, with greater 

 admiration than ever I did in my life before, the circulation of the blood in 

 many different parts. And when I contemplated the end of the bone, I saw 

 that very near to the jointing of the last joint, many small veins there met to- 

 gether, and formed a large one, when I took it for granted, that there was a 

 valvula, for there was a strange and quick pushing forwards after such a man- 

 ner, as if we saw our blood pushed forwards in an artery before our eyes. In 

 short, this contemplation far exceeded all the strange and pleasant ones, that 

 ever mine eyes beheld before. When I turned my eyes towards the fins near 

 the head, it was also very pleasant to see the blood run in many sorts of vessels, 

 and also underneath the head between the jaw-bones. After this I observed the 

 place of the heart ; when I saw, with no less admiration, the quick motion of 

 the heart, as well in the systole as diastole, whereby the heart was pushed 

 forward. 



I wrote, in my letter of the 10th of July, 1696, of my discovery concerning 

 the procreation or engendering of mites, which are very small and despicable 

 animals, and yet do a great deal of mischief; for by their numberless pro- 

 creation they consume flowers, seeds, flesh and bacon, and chiefly that which 

 is smoked and dried ; and all sorts of dried fruit, as figs, raisins, prunes, &c. 

 Lately examining the mites among some barley,* I saw, with admiration, that 

 some of these mites were of a quite difterent make from what I had seen before; 

 for they bad on their back some brownness, and their bodies had not so long 

 hairs on them as the common ones, and the hind part of their body was of 

 difl^erent shape ; they had also 8 paws, and before, near their head, were two 

 tools, much thicker than their paws, but not half so long, which were divided 

 towards their eTids, into finger-like joints, and furnished with nails like claws; 

 one joint of which, that was the thickest, had on one side extremely small 

 teeth like a saw. I saw also a second kind of mites, different from the former, 

 which at first seemed to be like these ; but if you compared them with the former, 

 you would see that they were of another kind, that were sprung forth by mixing 



* Several species of mites are occasionally observed amoog substances of this kind. 



