November 3, 1921] 



NATURE 



3P9 



Forbes 's great opportunity to make marine in- 

 vestigations outside the British seas came in 

 1 841, when he was appointed naturalist on the 

 surveying ship Beacon engaged on hydrographic 

 work in the eastern Mediterranean. His dredgings 

 in the .^igean gave great results and led to the 

 well-known and much-discussed views on zones of 

 life in the sea which are always associated with 

 his name. He defined in the ^4igean eight zones 

 of depth, characterised by peculiar assemblages of 

 animals, and he conjectured that the zero of 

 animal life would probably be found somewhere 

 about 300 fathoms — the " azoic " zone — a con- 

 clusion which has since been found to be errone- 

 ous. His .^gean report was laid before the 

 British Association in 1843, arid, we are told, at 

 once raised the author to a high rank amongst 

 living naturalists. 



But perhaps Forbes 's most important work of 

 an oceanographic nature is the Geological Survey 

 Memoir, in which he traces the origins of the 

 British fauna and flora and their relations to geo- 

 logical changes in the past. He accounted, for 

 example, for the five sub-floras which he defined 

 as due to successive migrations from neighbour- 

 ing lands previous to the isolation of the British 

 Islands from the mainland of Europe. He showed 

 the northern and southern relations of the fauna 

 of our seas, as exemplified by the fishes and the 

 molluscs, and the presence of "Boreal outliers," 

 assemblages of northern species occupying deeper 

 areas of 80 to 100 fathoms on the west of Scot- 

 land. These he regarded as portions of the 

 riginal northern fauna which formerlv occupied 

 our seas and had retreated northwards when the 

 climate became more genial subsequent to the 

 Glacial epoch, leaving these colonies isolated in 

 the deeper holes. Forbes 's theories on distribu- 

 tion and on the origin of the British fauna and 

 flora, even if in part erroneous, were a notable 

 contribution to knowledge, and far in advance of 

 anything known at the time, ^nd had an important 

 influence on the history of further investigation. 

 His theories, along w-ith his descriptive work, 

 form a wonderful output both in quantity and 

 quality for a man to have produced who died 

 before reaching the age of forty, onlv six months 

 after he had attained to the goal of his ambition, 

 the chair of natural histor\- in the University of 

 Edinburgh. 



Forbes was the most original, brilliant, and in- 

 spiring naturalist of his day, with a broad, philo- 

 sophic outlook over Nature, and a capacitv fc 

 investigating border-line problems involving 

 several branches of science — he was, in a word, 

 a pioneer of oceanography and the spiritual 

 ancestor of men like Sir Wyville Thomson and 

 Sir John Murray. 



We now pass from this period of the early 

 marine naturalists to that of the later ocean- 

 ographers of the nineteenth centun.'. If Forbes 

 was the pioneer of shallow-water dredging, 

 Wyville Thomson played a similar part in regard 

 to the exploration of the depths of the ocean. 



NO. 2714, VOL. 108] 



His name will go down through tfie ages as the 

 leader of the famous Challenger expedition, by 

 far the most important scientific deep-sea explor- 

 ing expedition of all times. Wyville Thomson's 

 work was in direct continuity with that of Forbes. 

 It was Forbes who, on a basis of observations 

 then thought to be sufficient, but now known to 

 have been exceptional, placed the zero of life in 

 the sea at 300 fathoms, and it was Wvville 

 Thomson more than any man who proved that 

 Forbes 's views were in this respect erroneous, and 

 that many and varied living things inhabit the 

 greatest depths of the ocean. 



Charles \\'yville Thomson was born in 1830 

 at Bonsyde, near Linlithgow, and was in 

 every sense, by ancestrj' and by education, 

 a son of Edinburgh. Like Edward Forbes, 

 he started as a medical student, but, for- 

 tunately for oceanography, after about three years 

 of study, his health gave way, and he left medi- 

 cine for what was then supposed to be the less 

 strenuous pursuit of science. It is interesting to 

 trace how Thomson's earliest investigations on 

 fossils led on by successive steps to the novel and 

 fruitful field of deep-sea exploration. Palaeonto- 

 logical observations on Crinoids suggested work 

 on the living Antedon, and that led to the in- 

 vestigation of the stalked larval stages of that 

 Rosy Feather Star. Then the news that a strange 

 new stalked Crinoid {Rhizocrinus loiotensis), re- 

 lated to the fossil .\piocrinidae, and resembling 

 the larval forms of Antedon, had been found living 

 in northern seas induced him in 1866 to visit Prof. 

 M. Sars at Christiania and examine for himself 

 the remarkable collection of rare animals that the 

 son, G. O. Sars, had brought up from more than 

 300 fathoms in the Lofoten fiords. Thomson was 

 naturally much struck by their novelt}- and interest 

 and their resemblance to extinct animals of former 

 geological periods. Thus inspired, he urged his 

 friend, Dr. W, B. Carpenter, with whom he was 

 then working, to join him in endeavouring to 

 promote an expedition to explore the deeper water 

 of the Atlantic. Carpenter's powerful advocacy 

 induced the council of the RoyaJ Society to use 

 their influence with the Hydrographer with such 

 success that the Admiralty placed first one and 

 then another small surveying steamer at the dis- 

 posal of a scientific committee. Thus came about 

 the cruises of the Lightning in 186S (when they 

 dredged down to 650 fathoms) and the Porcupine 

 in 1869 and 1870 (when they reached the great 

 depth of 2435 fathoms) which are described in 

 detail in Wyville Thomson's book, "The Depths 

 of the Sea," the first general text-book of ocean- 

 ography, published just after the Challenger had 

 sailed in 1872. These explorations showed an 

 abundance of life at all depths. 



Incidentally we may note that another Edin- 

 burgh professor — Fleeming Jenkin, the engineer — 

 when repairing a cable in the Mediterranean in 

 i860 brought up some sessile animals attached 

 to the broken cable from more than 1000 

 fathoms. 



