240 History of Luminescence 



found abundant life by sounding at 400 fathoms. Michael Sars 

 (1805-1869) in 1850 and his son, G. O. Sars (1837-1927) in 1864, 

 also described organisms at 400 fathoms. 



However, Charles Wyville Thomson (1830-1882) must be credited 

 with really extensive exploration of the ocean bottom. In his book, 

 The Depths of the Sea (1872) , the collections of the British Admir- 

 alty ships, " Lightning " and " Porcupine " are described. During 

 the summers of 1868 to 1870, the "Lightning" found life at 600 

 fathoms and the " Porcupine " at 2,435 fathoms in the Bay of Biscay, 

 thus completely revising the older ideas regarding the floor of the 

 ocean. Moreover, a surprisingly large number of deep sea forms 

 turned out to be luminous. Speaking of depths from 557 to 584 

 fathoms west of Ireland, Thomson (2nd ed., p. 98 and 149) wrote: 

 " In some places nearly everything brought up seems to emit light 

 and the mud was perfectly full of luminous spaces. ... It is difficult 

 to doubt that in a sea swarming with predaceous crustaceans . . . 

 phosphorescence must be a fatal gift." 



Thompson also described the singular sea pen, Pavonaria quadran- 

 gularis found at 100 fathoms in the Sound of Skye near Loch Tor- 

 ridon. They 



were resplendent with a pale lilac phosphorescence like the flame of 

 cyanogen gas; not scintillating like the green light of Ophiacantha, but 

 almost constant, sometimes flashing out at one point more brightly and 

 then dying gradually into comparative dimness. . . . The stems were a 

 metre long, fringed with hundreds of polyps. 



The seventies, eighties, and nineties were marked by many expedi- 

 tions of different nationalities to study the ocean depths in various 

 parts of the world. The British "Challenger" (1872-1876), the 

 U. S. " Tuscarora " (1872-1876) , " Blake " (1877-1880) and " Alba- 

 tross " (1891, 1899-1900), the French " Travailleur " and "Talis- 

 man " (1880-1883) , the Italian " Washington " and " Vettor Pisani " 

 (1881-1885) , the " Hirondelle " and " Princess Alice " (1885) of the 

 Prince of Monaco, the German Plankton expedition of Viktor 

 Hensen in the "National" (1889) and the German " Valdivia " 

 (1898-1899) under the direction of Carl Chun, The Danish " In- 

 golf" (1895-1896) and the Dutch " Siboga " (1899-1900) of Max 

 Weber. 



Of these, the " Challenger " expedition, with a staff of six natur- 

 alists under C. Wyville Thomson, was the most noted. Its collec- 

 tions were worked over by a group of specialists under John Murray 

 (1841-1914) and the results published in fifty thick folio volumes. 

 In Thompson's Voyage of the Challenger (London, 2 v., 1877) , and 



