80 
THE VOYAGE OF H.M.S. CHALLENGER. 
Hooker's 
Observations on 
Antarctic 
Diatoms. 
The Horizontal 
and Vertical 
Distribution or 
Organisms 
INITIATED. 
reference to Sir J C. Ross’s Antarctic Expedition, calling attention to the importance of 
observing the microscopic organisms, which Ehrenberg had shown played so important a 
riMe in the constitution of terrestrial strata. Hooker first made known some of the 
results of Ross’s deep-sea dredgings and investigations in 1 845, 1 and fuller details were given 
by Ross himself in the account of the voyage published in 1847. Hooker observed 2 that 
the w iter and ice of the Antarctic regions swarmed with Diatoms to such an extent that they 
.jure the water a brown tint. Between lat. 50° and 70° S. prodigious quantities of them 
were found, and in lat. 80" S. all the surface ice, the sides of the icebergs, and the base of 
the great Victoria Barrier within the reach of the waves, were coloured brown by these 
organisms. He observes that the siliceous skeletons must, after the death of the 
organisms, form siliceous deposits of considerable extent around all coasts bordered with 
ice, at depths between 80 and 400 fathoms. Opposite Victoria Barrier the bottom was 
covered with a white or greenish mud, consisting principally of Diatom frustules. In 
very deep water, opposite Victoria and Graham’s Land, the mud was very pure and fine 
grained, but in shallow water, near the coast, it was mixed with sandy and gravelty 
parti' les. Hooker considered that these microscopic plants were intended to maintain in 
the south Polar regions the balance between the animal and vegetable kingdoms, and also 
,o purify the vitiated atmosphere, performing in Antarctic latitudes the part of plants 
in other regions. He states that Diatoms exist in every latitude from Spitzbergeu to 
Victoria 1 -and, Iceland, Great Britain, the Mediterranean, North and South America, and 
the islands of the South Sea, and that the frustules of species living in the Antarctic have 
'•ontnbuted to the formation of various strata during geological periods. He estimates 
h i the deposit formed principally of Diatom frustules extends continuously for more 
than 400 miles off Victoria Land, at depths of about 300 fathoms. The existence of 
r main- of Diatoms, including a few Antarctic species, in volcanic ashes, pumice, and 
scoria;, led him to suppose that organic substances covering the bases of active volcanoes, 
like M->unt Lrebus and Vesuvius, might be ejected from the craters along with volcanic 
products. 
The researches of Ross and even those of Ehrenberg cannot be said to have established 
any important generalisation. The advantages to be derived from a knowledge of the 
horizontal and vertical distribution of the organisms living under the waters of the sea 
at greater or Ess distances from the shore do not appear to have been at first understood. 
However, as fur back as 1838, H. T. de la Beche inserted, in his Recherches sur le partie 
theorique de la geologic, a map by Brodrip indicating the localities and the depths at 
which living specimens of shellfish had been found in the sea and at the mouths 
of rivers. 
Ri.s o, whose observations were made in the Gulf of Genoa, was the first to distinguish 
1 Ann. awl May. Nat. Hint., ner. i., vol. xvi. p. 238, 1845. 
* lirxi Au. Report for 1847, Tram, of Section*, j>. 83 ; see also Flora Antarctica, London, 1847. 
