DISCOLORATION OF THE ARCTIC SEAS. 315 



pp. 91-96, and vol. ii., Appendix, by Dr. Dickie, pp. cxcviii., &c.). 

 Though one Diatom, as I have remarked, predominates, yet there 

 are, besides Protozoa, vast multitudes of many different species of 

 Diatoms, as shown (loc. cit.)* by Dr. Dickie (now of Aberdeen). 



Is it carrying the doctrine of final causes too far to say these 

 Diatoms play their part in rendering the frozen north accessible 

 to the bold whalemen, as I shall presently show they do in 

 furnishing subsistence for the giant quarry which leads him 

 thither ? 



I have spoken of the discoloured portions of the Arctic Sea as 

 abounding in animal life, and that this life was nowhere so abun- 

 dant as in those dark spaces which, as I have already demonstrated, 

 owe this hue to the Diatomacem in question. 



These animals are principally various species of Beroidce, and 

 other Steganophthalmous Medusae ; Entomostraca, consisting 

 chiefly of Arpacticus Kronii, A. chelifer and Cetochilus arcticus 

 and septentrionalis, and Pteropodous Mollusca — the chief of which 

 is the well-known Clio boj^ealis, though I think it proper to 

 remark that this species does not contribute to the Whale's food 

 nearly so much as we have been taught to suppose. The dis- 

 coloured 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 

 DiatomacetB 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 the Diatom, so that in reality the great things of 

 the sea depend for their existence upon the small things thereof! 

 I subsequently found (though the observation is not new) that 

 the alimentary canals of most of the smaller Mollusca, Echino- 

 dermata, &c. were also full of these Diatomacece. I also made 

 an observation which is confirmatory of what I have advanced 

 regarding the probability of these minute organisms giving off 

 en masse a certain degree of heat, though in the individuals 

 inappreciable to the most dehcate of our instruments. On the 

 evening of the 4th of June, this present year (1867), in latitude 

 67° 2Q' N., the sea was so full of animal (and Diatomaceous) life, 

 that in a few minutes upwards of a pint measure of Entomo" 

 straca, Medusce, and Pteropoda would fill the towing net. The 

 temperature of the sea was then by the most delicate instruments 

 found to 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 



See pages 319, 320 ; and further on. 



