Sentence:  There is no warm current, or if one, a very feeble one, flowing out of the South Atlantic. Most of the drift matter borne upon the ice-bearing current into that sea finds its way to the equator, and then into the veins which give volume to the Gulf Stream, and supply the <WSD>sargasso</WSD> of the North Atlantic with extra quantities of drift. The <WSD>sargassos</WSD> of the South Atlantic are therefore small. 
Meaning of the word marked with <WSD> tags:  A brown alga, of the genus "Sargassum", that forms large, floating masses.