found in the Waters of Harroivgate and Askern. 109 



the same manner as water is found of a green colour and ha- 

 ving green deposits, from the presence of the Cercaria viridis, 

 the green matter of Priestley. 



From this time I looked out more particularly for this red 

 substance, and soon found that it occurred very extensively in 

 the ditches and pools at and near Askern. Its appearance is 

 however very fluctuating, sometimes covering a large surface 

 of the bottom of the pool with the appearance of red velvet, 

 at other times not a spot is to be seen. At first I did not 

 suspect at all the connection of this animalcule with the sul- 

 phur springs, until I observed it most abundant in the water- 

 courses that received the overflowings of the pumps and wells 

 used for drinking and bathing. This induced me to examine 

 the water or mud in which I afterwards found it to occur, and 

 I invariably found, on dipping in a piece of silver coin, that it 

 presented the usual action of sulphuretted hydrogen. So con- 

 stantly has this been the case, that by this means I have de- 

 tected sulphuretted hydrogen in spots where I should not have 

 thought it existed. In the red colour before alluded to of the 

 deposits around the sides of the wells at Harrowgate, I recog- 

 nised the same substance as existed at Askern. Whilst at 

 Knaresborough, I observed this rose-coloured matter in the 

 mud of the water before it passes into the rock which forms 

 the dropping-well ; and on plunging a shilling into the mud, 

 it came out presenting the usual discoloration from sulphu- 

 retted hydi'ogen. 



The animalcule is very minute, not more than the ten 

 thousandth of an inch in diameter. Its form is oblong, fre- 

 quently presenting a contraction in the middle of its body, 

 and presenting from two to ten or twelve stomachs. Its line 

 of movement is straight, with a somewhat serpentine move- 

 ment of the body. 



On looking over Ehrenberg^s great work on Infusoria, I 

 have not been able to refer it to any of the genera there given, 

 although from its size and the circumstance of its producino- 

 a red deposit, it would seem to be his Astasia hcematodes. I 

 cannot, however, distinguish in it a tail, which is a generic 

 character of Astasia. The A. hcematodes was discovered by 

 Ehrenberg at the bottom of a lake in the steppe of Platow in 

 Siberia. 



I have frequently found another animalcule with this and 

 sometimes alone, forming a deposit of a much lighter colour, 

 having a whitish red or brickdust colour. It is a much longer 

 animal, and has the motions of a Vibrio, but not its bead-lTke 

 form. It possesses from ten to twelve stomachs. 



Both these animalcules live in water artifically impregnated 



