Cn a Fi/h-Pond in Norway-. 401 



the fo called Gr'o'7ij1:e, which in fpring is fecn in the Nor- 

 wegian feas ; efpecialiy as it rifes or falls according to the 

 heat or coUh The uncommon colour in water, which I 

 have here defcribed, is a remarkable phenomenon ; and, 

 during the eleven years I refided in the neighl)ourhood, I 

 never faw or heard of any change of the like kind in other 

 fifli-ponds. I therefore paid more attention to it, and efpe- 

 cially as in former times fuch appearances were confidered 

 as portending wars and bloodfiied : but thefe fuperftitious 

 notions muft lofe all credit when the above explanation is 

 adopted, and when the fecrets of nature are more accurately 

 explored. In regard to the caufe of this phenomenon I muft 

 confefs that to me it is inexplicable; and that it is eafier to 

 fay what it is not, than what it is. It is well known that 

 the quality of the atmofphere, fome years, can produce 

 worms and infers in incredible numbers : but what kind 

 of weather is neceflary for the generation of thefe infufion 

 animals, and whether a continual alternation of rain and 

 fun-fliine, which was the cafe in the fummer above men- 

 tioned, contributes to the phenomenon, is difficult to be 

 determined. 



P. S. The red matter continued on the water during the 

 whole month of Auguft, and feemcd ftill thicker ; but the 

 red particles were fmaller, and feemed entirely deftitute of 

 life. The corrupted and green water below fwarmcd, on 

 the other hand, with the ccrcarite already mentioned ; which 

 fometimes appeared of a triangular and fometimes of a cir- 

 cular form, as already faid. Some green (lime was obferved 

 alfo in the red matter; which however did not proceed from 

 the latter by a change of its colour from red to green, as I 

 at firft fuppofed, but was either a (limy fubftance arifing 

 from the decompoft:d green ccrcari^, or fome other cor- 

 rupted flime, which partly kept itfelf feparate from the red 

 matter, and partly mixed itfelf with it and difappcared. At 

 ^ny rate, 1 found in it no red, but hero and there a fhrunk 

 and wrinkled arcariu : but it muft be obferved, that what I 



Vol. IV. Dd have, 



