BATHYBIUS, a slimy substance, at one time supposed to exist in great masses in the depths of the ocean, and to consist of undifferentiated protoplasm. Regarding it as an organism which represented the simplest form of life, Huxley, about 1868, named it Bathybius Haeckelii. But investigations carried out by the "Challenger" expedition indicated that it was a flocculent pre cipitate of gypsum thrown down from sea-water by alcohol, and the hypothesis of its organic character was abandoned by most biologists, Huxley included.