176 THE OCEAN RIVER 



crustaceans, or krill, of the plankton. William Scoresby on 

 his North Polar expedition in 1820 dipped up some discolored 

 water and found that it contained great numbers of micro- 

 scopic objects called diatoms. But it was not until 1847 that 

 diatoms were first recognized as plants by the English botanist 

 Sir Joseph Hooker, who, after exploring the Antarctic seas 

 with Sir James Clark Ross, drew attention to their importance 

 in the ocean pastures. 



The first real advances in our knowledge of plankton were 

 made possible by a very simple and obvious invention. Where- 

 as early explorers were content to dip water from the sea in 

 buckets or canvas bags in order to examine the plankton con- 

 tained in it, the German scientist Johannes Muller in 1845, 

 hit upon the use of fine gauze or silk nets that could be towed 

 behind a vessel and so strain out the microscopic life. With a 

 few improvements, this method of concentrating plankton 

 is used in all modern scientific investigations of the drifting 

 sea life. 



The first organized expeditions for studying ocean life in the 

 Atlantic were prompted not entirely by interest in plankton 

 but partly by the desire to settle a controversy. It had long 

 been assumed that the deep, dark ocean floors were muddy 

 deserts of the ocean, completely devoid of life. When sub- 

 marine cables were invented, however, and the recovery of 

 broken cables showed undoubted evidence of marine life 

 growing on them, it was decided to settle the mystery of the 

 deep ocean floor once and for all. Edward Forbes, the great 

 pioneer of oceanography, had much to do with fomenting a 

 fever of interest, as a result of which H.M.S. Lightning in 1868 

 and H.M.S. Porcupine in 1869 were fitted out for deep-sea 

 dredging under Wyville Thompson. The results showed un- 

 questionably that there is fairly abundant and varied animal 

 life even in deep water, and that only the plants are restricted, 

 because of their need for light, to the lesser depths. 



