GM ERIGI E ee 
DISCOLORATION OF THE ARCTIC SEAS. 81 
to suppose. The discoloured sea is sometimes perfectly thick with the 
swarms of these animals, and then it is that the whaler’s heart gets 
glad as visions of “size whales” and “ oil money” rise up before him, 
for it is on these minute animals that the most gigantic of all known 
beings solely subsists. What, however, was my admiration (it was 
scarcely surprise) to find, on examining microscopically the alimentary 
canals of these animals, that the contents consisted entirely of the 
Diatomacee which give the sable hue to portions of the Northern Sea 
in which these animals are principally found! It thus appears, that 
in the strange cycle of nature, the “ whales’ food” is dependent on 
this diatom! I subsequently found (though the observation is not 
new) that the alimentary canals of most of the smaller Mollusca, 
Echinodermata, etc., were also full of these Diatomacee. I also made 
an observation which is confirmatory of what I have advanced regard- 
ing the probability of these minute organisms giving off en masse a 
certain degree of heat, though in the individuals inappreciable to the 
most delicate of our instruments. On the evening of the 4th of June, 
1867, in latitude 67° 26’ N., the sea was so full of animal (and diato- 
maceous) life, that in a few minutes upwards of a pint measure of 
Entomostraca, Meduse, and Pteropoda would fill the towing-net. The 
temperature of the sea was then by the most delicate instruments found 
be 32:5? Fahr., and next morning (June 5th), though the air had 
exactly the same temperature, no ice at hand, and the ship maintained 
almost the same position as on the night previous, yet the surface 
temperature of the sea had sunk to 27°5° Fahr., and was clear of life, 
—so much so, that in the space of half an hour the towing-net did not 
capture a single Entomostracon, Medusa, or Pteropod. 1 also found 
that this swarm of life ebbed and flowed with the tide, and that the 
whalers used to remark that whales along shore were most frequently 
caught at the flow of the tide, coming in with the banks of whales’ 
food. This mass of minute life also ascends to the surface more in 
the calm arctic nights when the sun gets near the horizon during the 
long, long summer. In 1860 I was personally acquainted with the 
death of thirty individuals of the “right whalebone whale” (Balena 
mysticetus, L.), and of this number fully three-fourths were killed be- 
tween ten o’clock p.m. and six o’clock a.M., having come on the 
“whaling grounds " at that period (from amongst the ice where they 
had been taking their siesta), to feed upon the animals which were 
VOL. vi. [marcy 1, 1868. ] - 
