. 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. "Michael Sars" North Atlantic Deep-sea Expedition (1910); Oceanography; North Atlantic Ocean. PELAGIC PLANT LIFE 321 mass in the middle, and become enwrapped in a new thick wall of characteristic shape within the old cell-wa carded as soon as the resting-spore is completely developed (see Fig. 223). The spores have now ac- quired an increased specific weight, as compared with their original cell, an
. 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. "Michael Sars" North Atlantic Deep-sea Expedition (1910); Oceanography; North Atlantic Ocean. PELAGIC PLANT LIFE 321 mass in the middle, and become enwrapped in a new thick wall of characteristic shape within the old cell-wa carded as soon as the resting-spore is completely developed (see Fig. 223). The spores have now ac- quired an increased specific weight, as compared with their original cell, and sink down into deep water, where they may be found months after they have disappeared from the surface-layers. The majority of them, however, rest on the bottom in shallow coastal waters, until con- ditions of existence again occur which induce them to make a fresh start. The germination of the resting- spores has not yet been described, though Hensen states that Lohmann has observed the first stages on several occasions. It will be a great advantage when we can follow their development-history through all its stages, and study the conditions of existence that lead to germination. Resting-spores are unknown in the true oceanic species ; but, as already stated, they are found in most of the species belonging to coastal seas, not aware of them till quite a short ^hich. Fig. 223.— Chain of Chmtoceras constrictum, with three rest- ing - spores and one normal cell (the end - cell of the CHAIN) {*-r-).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Murray, John, Sir, 1841-1914; Hjort, Johan, 1869-; Appellöf, Jakob Johan Adolf, 1857-; Gran, H. H. (Haakon Hasberg), 1870?-; Helland-Hansen, Bjørn, 1877-. London : Macmillan
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherlondo, bookyear1912
