Under the most favorable conditions these movements, as seen under the microscope, make a perfect torrent of unceasing activity, and introduce us to one of the wonderful sights of which students of biology have so many. Huxley (with slight verbal alterations) says: "The spectacle afforded by the wonderful energies imprisoned within the compass of the microscopic cell of a plant, which we commonly regard as a merely passive organism, is not easily forgotten by one who has watched its movement hour by hour without pause or sign of weakening. The possible complexity of many other organisms seemingly as simple as the protoplasm of the plant just mentioned dawns upon one, and the comparison of such activity to that of higher animals loses much of its startling character. Currents similar to these have been observed in a great multitude of very different plants, and it is quite uniformly believed that they occur in more or less perfection in all young vegetable cells. If such be the case, the wonderful noonday silence of a tropical forest is due, after all, only to the dullness of our hearing, and could our ears catch the murmur of these tiny maelstroms as they whirl in the innumerable myriads of living cells that constitute each tree, we should be stunned as with the roar of a great city." The Essential Steps in Recognizing the Likeness of Protoplasm in Plants and Animals Dujardin.--This substance, of so much interest and importance to biologists, was first clearly described and distinguished from other viscid substance, as albumen, by Félix Dujardin in 1835. Both the substance and the movements therein had been seen and recorded by others: by Rösel von Rosenhof in 1755 in the proteus animalcule; again in 1772 by Corti in chara; by Mayen in 1827 in Vallisnieria; and in 1831 by Robert Brown in Tradescantia. One of these records was for the animal kingdom, and three were for plants. The observations of Dujardin, however, were on a different plane from those of the earlier naturalists, and he is usually credited with being the discoverer of protoplasm. His researches, moreover, were closely connected with the development of the ideas regarding the rôle played in nature by this living substance.