VOL. XXIII.] PHILOSOPHICAL TRANSACTIONS. 7 



and then gently extended them again ; and this kind of motion they continued 

 a great while. 



PI. 1, fig. 6,* ABC represent one of the green weeds, of a common size, as 

 it lay upon the water, and appeared to the naked eye. Fig. 7, depg show the 

 same weed as it appeared in the glass tube filled with water, with its roots ex- 

 tended ; fig. 8, HiKLMNOPaR represent a small part of the said root, as it ap- 

 peared in the microscope, through the whole length of which were to be seen 

 its vessels with their divisions; which roots I imagine were of no further use, 

 and in a manner withered ; they were also overgrown with a great many parti- 

 cular long particles, and mostly with little figures like flowers, as are repre- 

 sented in the fig. between k and l. The animalcula beforementioned, are to be 

 seen like little bells, at lst and nvw ; 1 saw above a hundred of these animal- 

 cula, with their tails fastened to the root, and living, between hiklm, but other 

 roots had none of them. 



Jn several of these roots I observed one, and some few times two sheaths, or 

 cases fastened in them, of several sizes, the largest is represented by rxzy. 

 Out of the same sheath appeared a little animal, -(- the fore-part of whose body 

 was roundish, as in xzy ; and presently from the same rotundity proceeded 2 

 little wheels, that had a swift gyration, always one and the same way, as in 

 abc ; these small wheels were as thick set with teeth, as the wheel of a watch ; 

 and when these animalcula had for some time exerted their circular motion, they 

 drew their wheels into their body, and their body wholly into their sheaths, and 

 then soon after thrust them out again with the aforesaid motion ; another while 

 they remained as it were shut up in their shells ; and though 1 observed the same 

 wheels in other animalcula also, yet their bodies differed from each other, and 

 their sheaths were of a darkish colour, so that I could not easily perceive the 

 animalcula ; and they seemed to be composed of globules. 



I observed also other sheaths, that were several degrees smaller than those 

 beforementioned, and as transparent as glass, so that one might plainly see the 

 animalcula lying within them. 



Fig. 8, pdef represent the sheath with the little worm pdf in it : in the 

 same figure, ogh show a sheath with half the body of the same animalcule 

 gh protruded out of it ; and in which, by reason of its exceeding smallness, 

 the wheels could only be seen now and then, and that only when the body was 

 extended, which would soon be compressed or shrunk up ; and about the middle 

 of the body of one of these, which I conceived to be the lower part of its belly, 



* This plant is the lemna polyrhiza. Lin. or greater duckweed. f A species of vortieeNa. 



