318 R. BROWN ON THE NATURE OP THE 



most interested in its existence, illustrating in a remarkable degree 

 how Nature is in all her kingdoms dependent on all, and how great 

 are little things! 



Note. — Prof. Nordenskiold offers the following remarks on 

 the Colour of the Arctic Seas, in his " Expedition to Greenland," 

 " Geological Magazine," vol. ix., pp. 9, 10 : — 



Hudson, and other veteran mariners of the Arctic seas, mention 

 the variety of colours that distinguish the water in certain parts, 

 which are frequently so sharply distinguished that a ship may 

 sail with the one side in blue and the other in greyish-green 

 water. It was at first supposed that these colours were indications 

 of different currents — the green of the Arctic, the blue of the 

 Gulf-stream. Later, Scoresby affirmed that the phenomenon arose 

 from the presence of innumerable organisms, which he seems to 

 consider as Crustacea, in the water. This observation has since 

 been continued, partly by the former Swedish Arctic Expedition, 

 and partly by Dr. Brown,* during the voyages made by him in 

 the Arctic seas as surgeon in a whaler, and as a member of 

 Whymper's Expedition. We also endeavoured to divert the 

 tedious monotony of the voyage by observations on this pheno- 

 menon. 



The sea-water in the neighbourhood of Spitzbergen is marked 

 by two sharply distinguished colours — greyish-green and fine 

 indigo-blue. In the Greenland seas we also find water with a 

 very decided shade of brown. These colours are seen most pure 

 if one looks vertically down from the ship to the surface of the 

 water through a somewhat long pipe. The green, or rather grey- 

 green, water is generally met with in the neighbourhood of ice 

 (whence it was supposed to arise from the Arctic Current) j the 

 blue where the water is free from ice ; the brown, as far as I am 

 aware, chiefly in that part of Davis Strait which is situated in 

 front of Fiskernaes. When specimens of the water are taken up 

 in an uncoloured glass, it appears perfectly clear and colourless, 

 nor can one with the naked eye discover any organisms to account 

 for the colour. But if, when the velocity of the ship allows of it 

 (i.e., when the ship makes from one to three knots an hour), a 

 fine insect-net be towed behind the ship, in the green and brown 

 water, it will soon be found covered with a film of — in the former 

 case green, in the latter case brown slime, of organic origin, and 

 evidently the real cause of the abnormal colour of the sea-water. 

 Just in these parts may be found swarms of small Crustacea, 

 which live upon this slime, and in their turn, directly or indirectly, 

 become the food of larger marine animals. The blue water, on 

 the contrary, at least in these seas, deposits no slime upon the 

 insect-net, and is far less frequented by Crustacea, Annelides, &c. 



* A very interesting essay on the subject has been published by Dr. Brown. 

 The Farmer, Jan. 1, 1865, p. 16. See above, p. 31 1. 



