674 PHILOSOPHICAL TRANSACTIONS. [aNNO 1742-3. 



relating to the perimeter of the figure, its area, the solid generated by this 

 area, &c. with examples of this kind concerning the solid of least resistance ; 

 and concludes with an instance of the theorems by which the value of the ordi- 

 nate may be determined from the value of the area, by common algebra, and by 

 observing, that it is not absolute, but relative space and motion, that is supposed 

 in the method of fluxions. 



Observations on the Mouth of the Eels* in Vinegar, and also a strange j4quatic 

 Animal ; in a Letter from the Rev. Mr. Henry Miles to Mr. Baker, F. R. S. 

 ■^ N° 469, p. 416. 



This observation was made with the camera obscura microscope : first, in a 

 very small tube, Mr, M. put a small quantity of vinegar, with several anguillae: 

 at first sight of the image on the screen, one had a motion as if it had been 

 wounded, about the middle of the back ; it neither rose nor sunk in the liquor, 

 but lay in this form -^==5*-^ , wriggling itself, as if giving signs of pain, and would 

 soon expire, which it accordingly did in a minute's time ; but it coiled itself up, 

 and stuck to the side of the tube very close. He put out the liquor, after wait- 

 ing to see whether it would revive, in vain, and viewed it several times in the 

 common light, in which way he had the most distinct appearance. The larger 

 end, which may be called the head, was stretched out from the rest of the body, 

 a little way, as in the figure, which gave an opportunity of examining what 

 mouth it had. On the first view of it in common light, he saw what he thought 

 may be called the mouth : repeated trials in difli^erent lights and positions, and 

 with different magnifiers, confirmed the suspicion. After the strictest and most 

 exact observation he could discern it to be nothing more than a transparent 

 tube. Where the instruments of nutrition, and the springs of life, are, he 

 doubts not we shall soon discover. 



In this figure, a is the mouth, which seemed to be as wide open as 

 ' a it possibly could be. The figure is too small to give a just idea of the 

 shape of the mouth, but it had the appearance which a tube, or 

 rather a cone, would make cut slopewise. 



: Mr. H. Miles also sent some specimens of an odd aquatic animal,-^ found in 

 standing water : he kept some of them in their own element in the house, but 

 they all died in a day and half's time. They seem to be nothing but skin, and 



• The vibrio aceti, Linn. Gmel. is sometimes considered as a variety only of the vibrio glutinis or 

 paste eel, from which it chiefly differs in being more slender and transparent. 



+ The supposed animal here described by Mr. Miles, is nothing more than the seed of the plant 

 called bidens tripartita, which usually grows in watery places, and the seeds of which have a kind of 

 elastic motion when touched. 



