BROWN, ON DISCOLORATION OF THE ARCTIC SEAS. 243 



occasion to notice the same appearance in similar latitudes 

 on the opposite shores of Davis' Straits where I had princi- 

 pally observed it in 1860. This observation holds true of 

 every portion of discoloured water which I have examined 

 in Davis' Straits, Baffin's Bay, and the Spitzbergen or 

 Greenland Seas, viz., that wherever the green water occurred 

 the sea abounded in Diatomacese, the contrary holding true 

 regarding the ordinary blue water. These swarms of dia- 

 toms do not appear to reach in quantity any very great depth, 

 for in water brought up from 200 hundred fathoms there were 

 few or no diatoms in it. They seem also to be affected by 

 physical circumstances, for, sometimes in places where a 

 few hours previously the water on the surface was swarming 

 with them, few or none were to be found, and in a few hours 

 they again rose. But the diatom I found plays another 

 part in the economy of the Arctic Seas. In June, 1860, 

 whilst the iron-shod bows of the steamer I was on board of 

 crashed their way through among the breaking-up floes of 

 Baffin's Bay, among the Women's Islands, I observed that 

 the ice thrown up on either side was streaked and coloured 

 brown, and on examining this colouring matter I found that 

 it was almost entirely composed of the moniliform diatom I 

 have described as forming the discolouring matter of the ice- 

 less parts of the icy sea. I subsequently made the same 

 observation in Melville Bay, and in all other portions of 

 Davis' Straits and Baffin's Bay where circumstances admitted 

 of it. During the long winter the Diatomacese had accumu- 

 lated under the ice in such abundance that when disturbed 

 by the pioneer prow of the early whalers they appeared like 

 brown slimy bands in the sea, causing them to be mistaken 

 more than once for the waving fronds of Laminaria longi- 

 cruris (De la Pyl.) (which, and not L. saccharina, as usually 

 stated, is the common tangle of the Arctic Sea). On examin- 

 ing the under surface^ of the upturned masses of ice, I found 

 the surface honey-combed, and in the base of these cavities 

 vast accumulations of Diatomaceae, leading to the almost 

 inevitable conclusion that a certain amount of heat must be 

 generated by the vast accumulations of these minute organ- 

 isms, which thus mine the giant floes, so fatal in their majesty, 

 into cavernous sheets. These are so decayed in many in- 

 stances as to be easily dashed on either side by " ice-chisels" 

 of the steamers which now form the greater bulk of the 

 Arctic-going vessels, and they get from the seamen, who 

 too frequently mistake cause for effect, the familiar name of 

 " rotten ice." I find that, as far as the mere observation 

 concerning the diatomaceous character of these slimy masses 



