Our Food From the Waters

Abstract

AT the last meeting of the British Association in Canada (Toronto, 1897) I was able to lay before Section D a preliminary account of the results of running sea-water through four silk tow-nets of different degrees of fineness continuously day and night during the voyage from Liverpool to Quebec. During the eight days' traverse of the North Atlantic, the nets were emptied and the contents examined morning and evening, so that each such gathering was approximately a twelve-hours' catch, and each day and each night of the voyage was represented by four gatherings. This method of collecting samples of the surface fauna of the sea in any required quantity per day or hour from an ocean liner going at full speed was suggested to me by Sir John Murray of the Challenger Expedition, and was first practised, I believe, by Murray himself in crossing the Atlantic. I have since been able to make similar traverses of several of the great oceans, in addition to the North Atlantic, namely, twice across the equator and through the South Atlantic, between England and South Africa, and four times through the Mediterranean, the Red Sea, and the Indian Ocean to Ceylon; and no doubt other naturalists have done much the same. The method is simple, effective, and inexpensive; and the gatherings, if taken continuously, give a series of samples amounting to a section through the surface layer of the sea, a certain volume of water being pumped in continuously through the bottom of the ship, and strained through the fine silk nets, the mesh of which may be one two-hundredth of an inch across, before passing out into the sea again. In examining with a microscope such a series of gatherings across an ocean, two facts are brought prominently before the mind: (1) the constant presence of a certain amount of minute living things; (2) the very great variation in the quantity and in the1 nature of these organisms.