VOL. VII.] PHILOSOPHICAL TRANSACTIONS. 7I 



inour. The fifth day (which was the day of the incision) it ran as on the 

 fourth, but left an extreme clamminess on the teeth, insomuch that they often 

 clave together, as though they had been joined together with glue. 



Upon the incision, which proved not wide enough, the membranes or bags, 

 wherein the stone lay, came away first. As to the stone itself it was so hard 

 as to endure the forceps in drawing it forth. It was covered over with grass- 

 green matter, which soon dried, and left the stone of a whitish colour. It is 

 but light in proportion to its bulk, weighing about 7 grains, and is much of 

 the shape of our ordinary horse beans. There are visible impressions upon it of 

 some capillary and small vessels where it was bred amongst. It is scabrous or 

 rough, sand-like, although the substance is tophaceous. 



The accidents accompanying the working away of this stone, (for the inci- 

 sion was merely obstetrical,) and the place of its birth, gave occasion to call the 

 distemper a ranula. Yet in truth this was nothing else but one of those tumours 

 called atheroma, and therefore we will name it lapis atheromatis. * 



Extract of a Letter from the same Mr. Lister, written from Vorky 

 April 12, 1672, concerning animated Hoi^se-hairs ; rectifying a 

 vulgar Error. N' 83, p. 4064. 



It has been credibly reported, that horse hairs thrown into water will be ani- 

 mated ; and yet I shall show you by an unquestionable observation, that such 

 things as are vulgarly thought animated hairs, are very insects, nourished within 

 the bodies of other insects, even as ichneumones are within the bodies of cater- 

 pillars. 



I will premise the particulars concerning this animal as I find them collected 

 by the industry of Aldrovandus, and save you the trouble of that voluminous 

 author. This insect, says he, seems to have been unknown to the ancients, 

 as it is called by the moderns seta aquatica or vermis setarius, either from the 

 very slender form of the body, or because it is thought to be generated of a 



/horse-hair putrifying in water. The Germans call them by a name rendered 

 vituli aquatici. 



It is bred in corrupt waters, perhaps of horse-hair, -j- for (says Albertus, upon 

 his own frequent trial, as I find him quoted by Aldrovandus,) these hairs, put 

 into standing water move and are animated, or, as he words it, vitam et spiri- 

 tum accipiunt, et moventur. Others have thought them to have their birth 



* Instances of sublingual calculi have been frequently recorded by writers on surgery. The term 

 atheroma seems to be little adapted to this case, 

 f Certainly not. See note at the end of this paper. 



