EXPEDITION OF THE CHALLENGER. 29 



most universally present, generally eludes the search of the naturalist ; except 

 when its species are congregated among that mucous scum which is sometimes 

 seen floating on the waves, and of whose real nature we are ignorant ; or when 

 the colored contents of tlie marine animals who feed on these algse are exam- 

 ined. To the south, however, of the belt of ice which encircles the globe, be- 

 tween the parallels of 50" and 70 south, and in the waters comprised between 

 that belt and the highest latitude ever attained by man, this vegetation is very 

 conspicuous, from the contrast between its color and the white snow and ice in 

 which it is embedded. Insomuch, that in the eightieth degree, all the surface- 

 ice carried along by the currents, the sides of every berg, and the base of the 

 great Victoria Barrier itself, within reach of the swell, were tinged brown, as if 

 the polar waters were charged with oxide of iron. 



" As the majority of these plants consist of very simple vegetable cells, in- 

 closed in the indestructible silex (as other algse are in carbonate of lime), it is 

 ol)vious that the death and decomposition of such multitudes must form sedi- 

 mentary deposits, proportionate in their extent to the length and exposure of 

 the coast against which they are washed, in thickness to the power of such 

 agents as the winds, currents, and sea, which sweep them more energetically to 

 certain positions, and in purity, to the depth of the water and nature of ^he 

 bottom. Hence we detected their remains along every ice-bound shore, in the 

 depths of the adjacent ocean, between 80 and 400 fathoms. OflT Victoria Barrier 

 (a perpendicular wall of ice between 100 and 200 feet above the level of the 

 sea) the bottom of the ocean was covered with a stratum of pure white or green 

 mud, composed principally of the silicious shells of the Diatomacem. These, on 

 being put into water, rendered it cloudy like milk, and took many hours to sub- 

 side. In the very deep water off Victoria and Graham's Land, this mud was 

 particularly pure and fine ; but toward the shallow shores there existed a 

 greater or less admixture of disintegrated rock and sand ; so that the organic 

 compounds of the bottom frequently bore but a small proportion to the inor- 

 ganic. ..." 



" The universal existence of such an invisible vegetation as that of the Ant- 

 arctic Ocean is a truly wonderful fact, and the more from its not being accompa- 

 nied by plants of a high order. During the years we spent there, I had been ac- 

 customed to regard the phenomena of life as diifering totally from what obtains 

 throughout all other latitudes, for every thing living appeared to be of animal 

 origin. The ocean swarmed with Mollusca, and particularly entomostratous 

 Crustacea^ small whales, and porpoises ; the sea abounded with penguins and 

 seals, and the air with birds ; the animal kingdom was ever present, the larger 

 creatures preying on the smaller, and these again on smaller still ; all seemed 

 carnivorous. The herviborous were not recognized, because feeding on a micro- 

 scopic herbage, of whose true nature I had formed an erroneous impression. It 

 is, therefore, with no little satisfaction that I now class the Diatomacem with 

 plants, probably maintaining in the South Polar Ocean that balance between the 

 vegetable and animal kingdoms which prevails over the surface of our globe. 

 Nor is the sustenance and nutrition of the animal kingdom the only function 

 these minute productions may perform ; they may also be the purifiers of the 

 vitiated atmosphere, and thus execute in the antarctic latitudes the office of our 

 trees and grass-turf in the temperate regions, and the broad leaves of the palm, 

 etc., in the tropics. ..." 



With respect to the distribution of the Diatomacece, Dr. Hooker 

 remarks: 



