. 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. Oceanography. PELAGIC PLANT LIFE 363 as 1200 of sea-water. It made 700 to 800 revolutions per minute, and after eight minutes the plants were all collected at the bottom of the glasses. Our next proceeding was to pour away the clear water, and after rinsing the deposit, to put it in a smaller glass with a tapering bottom, where it was subjected to the action of a small hand-centrifuge. In this way we coll
. 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. Oceanography. PELAGIC PLANT LIFE 363 as 1200 of sea-water. It made 700 to 800 revolutions per minute, and after eight minutes the plants were all collected at the bottom of the glasses. Our next proceeding was to pour away the clear water, and after rinsing the deposit, to put it in a smaller glass with a tapering bottom, where it was subjected to the action of a small hand-centrifuge. In this way we collected all the con- tents of, say, 300 of sea-water in one drop, which we examined in a counting chamber beneath the micro- scope, and noted carefully each single organism. As a rule we had to centrifuge the whole 300 , but, if the plankton was very abundant, 150 or even 100 might suffice. Examination with the microscope is always more difficult when the or- ganisms in the counting chamber lie close together. These investigations were carried Smallest out all the way from the Canaries to ^SSSSdant Newfoundland, and thence to the in the open Irish coast banks, and resulted in our discovering that the smallest organisms which pass right through the silk nets are far more abundant than the others in the open sea, while the larger diatoms and peridinese would appear to be so scanty that the total of all their species together only amounts to about ten per litre. Despite this fact, however, we found in the samples taken with our nets that there were at least fifty species fig. 251 - centrifuge Glasses of these larger forms at every station, and Pipettes for use with , 9 . in lohmann's hand-centrifuge, so that as far as species go the flora is exceedingly rich. We were also able in this way to determine the occurrence Amount of of algae at different depths. Samples from the surface, and Jjjj^fat from 20, 50, 75, and 100 metres were taken regularly, and depths. we als
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