Archive image from page 378 of The depths of the ocean. The depths of the ocean : a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic depthsofoceangen00murr Year: 1912 PELAGIC PLANT LIFE 143 the shores of Iceland, they commence to develop at a great rate, with the result that the plankton in those parts frequently yields abundant though monotonously uniform samples of these degenerate forms. The altered conditions of existence, which obviously must have supervened, have thus resulted in
Archive image from page 378 of The depths of the ocean. The depths of the ocean : a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic depthsofoceangen00murr Year: 1912 PELAGIC PLANT LIFE 143 the shores of Iceland, they commence to develop at a great rate, with the result that the plankton in those parts frequently yields abundant though monotonously uniform samples of these degenerate forms. The altered conditions of existence, which obviously must have supervened, have thus resulted in an extensive production of algse, though without investing them with their normal robust appearance. The strings of cells are of much smaller diameter than usual, so that the formation of auxospores cannot have taken place at the stage that is usual elsewhere. Wesenberg-Lund has told us that pelagic Lund. Fig. 244. la, ChcBtoceras laciniosum : ifi, forma pelaica ; 2a, C. schiittii : zb, forma oceanica. fresh - water diatoms, such as Asterionella gj'-acillinia and Fragilaria crotonensis, keep on reducing their dimensions in the Danish lakes for months, sometimes even for over a year, and then suddenly return to their maximum measure- ments, and that this is undoubtedly due to the formation of auxospores. All are not, however, affected alike by such a change, and the species occur thereafter in two different sizes, making it necessary to express the measurements of their cell-dimensions by means of divergent curves. This goes on uninterruptedly, moreover, and the smallest forms diminish and seem to degenerate more and more, until in Wesenberg- Lund's opinion they lose all power of regaining their normal
Size: 1649px × 1213px
Photo credit: © Actep Burstov / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: 1900, 1910, 1912, _michael_sars_north_atlantic_deep_sea_expedition_191, appell_f_jakob_johan_adolf_1857_, archive, book, bookauthor, bookcentury, bookdecade, bookpublisher, booksubject, bookyear, drawing, gran_h_h_haakon_hasberg_1870_, helland_hansen_bj_rn_1877_, historical, history, illustration, image, london_macmillan, murray_john_sir_1841_1914, north_atlantic_ocean, oceanography, page, picture, print, reference, vintage
