Archive image from page 397 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 362 DEPTHS OF THE OCEAN determining the species whose development we desire to trace ; consequently most of those who endeavour to work at these interesting questions will be forced to confine themselves to definite problems, and content themselves with tracing the growth of a limited number of species. No doubt a man like


Archive image from page 397 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 362 DEPTHS OF THE OCEAN determining the species whose development we desire to trace ; consequently most of those who endeavour to work at these interesting questions will be forced to confine themselves to definite problems, and content themselves with tracing the growth of a limited number of species. No doubt a man like Lohmann may be able to know all the species within certain limits, and may actually calculate by counting what each of them contributes to the total plankton volume, but speaking generally a ' uni- versal method ' that will give us the total quantity of all the plants and animals of the sea in curves and tables is un- attainable. During the ' Michael Sars ' Expedition our quantitative investi- gations yielded really remarkable results. Lohmann had suc- ceeded by means of a centrifuge in de- termining the quan- tity of plankton in quite small samples of Baltic water, and we felt confident, therefore, that this excellent method ought also to prove serviceable in the open sea. We very soon found, however, that the algae there were too scarce for our little hand-centrifuge (Fig. 250) to be of much utility; there was so little to be found at the bottom of the centrifuge glasses (Fig. 251) that we obtained a hope- lessly inadequate idea of the plant life, whereas in the stomachs of salpse we might, perhaps, get a quite abundant flora of small forms. Fortunately, we had taken with us a big centrifuge to be worked by steam (see Fig. 91, p. 105), and in its six glasses we could centrifuge at one time as much Fig. 250.—Lohmann's Hand-centrifuge.


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