n THE PROBLEMS OF THE DEEP SEA 51 



theless, so far as the limit of the range of life in 

 depth goes, Forbes' conclusion has been completely- 

 negatived, and the greatest depths yet attained 

 show not even an approach to a " zero of life " : — ■ 



" During the several cruises of H. M. ships Lightning and 

 Porcwpine in the years 1868, 1869, and 1870," says Dr. Wyville 

 Thomson, "fifty-seven hauls of the dredge were taken in the 

 Atlantic at depths beyond 500 fathoms, and sixteen at depths 

 beyond 1,000 fathoms, and, in all cases, life was abundant. In 

 1869, we took two casts in depths greater than 2,000 fathoms. 

 In both of these life was abundant ; and with the deepest cast, 

 2,435 fathoms, off the mouth of the Bay of Biscay, we took 

 living, well-marked and characteristic examples of all the five 

 invertebrate sub kingdoms. And thus the question of the 

 existence of abundant animal life at the bottom of the sea has 

 been finally settled and for all depths, for there is no reason 

 to suppose that the depth anywhere exceeds bettveen three and 

 four thousand fathoms ; and if there be nothing in the condi- 

 tions of a depth of 2,500 fathoms to prevent the full develop- 

 ment of a varied Fauna, it is impossible to suppose that even an 

 additional thousand fathoms would make any gi'eat difference,"^ 



As Dr. Wyville Thomson's recent letter, cited 

 above, shows, the use of the trawl, at great depths, 

 has brought to light a still greater diversity of life. 

 Fishes came up from a depth of 600 to more than 



1 The Depths of the Sea, p. 30. Results of a similar kind, 

 obtained by previous observers, are stated at length in the sixth 

 chapter, pp. 267-280. The dredgings carried out by Count 

 Pourtales, under the authority of Professor Peirce, the Super- 

 intendent of the United States Coast Survey, in the years 

 1867, 1868, and 1869, are particularly noteworthy, and it is 

 probably not too much to say, in the words of Professor 

 Agassiz, "that we owe to the coast survey the first broad and 

 comprehensive basis for an exploration of the sea bottom on a 

 large scale, opening a new era in zoolodcal and geological 

 research." 



