588 Dr. Daubeny on a certain Kind of 



deposit, which have served to throw a certain air of mystery 

 over its nature and origin. 



I am therefore induced to lay before this Society a drawing*, 

 which represents the appearances exhibited, under a micro- 

 scope of Amici's construction, by an organic substance which 

 I obtained hist summer at the hot spring of Greoulx in Pro- 

 vence (departement des Basses Alpes). This matter was found 

 everywhere on the pavements of the bathing-rooms, in parts 

 exposed to the splashing of the thermal water, which, for 

 the convenience of topical bathing, or the douche^ is usually 

 allowed to descend in a constant stream from an open pipe, 

 communicating with the reservoir which receives the mineral 

 water, and terminating just below the ceiling of the room, 

 through which it passes in a direction nearly perpendicular. 



The substance alluded to, seen by the naked eye, has a green- 

 ish tinge, and seems made up of bundles of filaments : under 

 the microscope, however, the latter are magnified into long 

 cylindrical tubes, almost transparent, and divided into articuli, 

 the length and diameter of which appear nearly equal, filled 

 with a darkish fluid, whilst the intervening spaces are nearly 

 colourless. This appearance may, perhaps, be explained by 

 supposing a double tube, the exterior one transparent and con- 

 tinuous throughout, the interior composed of articulations filled 

 with a coloured matter, and distinct one from the other, in con- 

 formity to the general structure of Conferva, as laid down by 

 Bory de St. Vincentt and others. These same filaments are 

 sometimes so disposed with reference one to the other, as to pre- 

 sent a stellated appearance of greater or less regularity. 



In fig. 5. of the plate representing Arthrodia, which is given 

 in the 2nd volume of the Dictionnaire Classique d' Histoire 



* The drawing is deposited in the Library of the Society, 

 t Diet. Classique (THist. Nat., article "yJrthrodiees." 



Natiirelle, 



