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.
Dujardin was a quiet modest man, whose attainments and service to the progress of biology have usually been under-rated. He was born in 1801 at Tours, and died in 1860 at Rennes. Being descended from a race of watchmakers, he received in his youth a training in that craft which cultivated his natural manual dexterity, and, later, this assisted him in his manipulations of the microscope. He had a fondness for sketching, and produced some miniatures and other works of art that showed great merit. His use of colors was very effective, and in 1818 he went to Paris for the purpose of perfecting himself in painting, and with the intention of becoming an artist. The small financial returns, however, "led him to accept work as an engineer directing the construction of hydraulic work in Sédan." He had already shown a love for natural science, and this led him from engineering into work as a librarian and then as a teacher. He made field observations in geology and botany, and commenced publication in those departments of science.
About 1834 he began to devote his chief efforts to microscopic work, toward which he had a strong inclination, and from that time on he became a zoölogist, with a steadily growing recognition for high-class observation. Besides his technical scientific papers, he wrote in a popular vein to increase his income. Among his writings of this type may be mentioned as occupying high rank his charmingly written "Rambles of a Naturalist" (Promenades d'un Naturaliste, 1838).
By 1840 he had established such a good record as a scientific investigator that he was called to the newly founded University of Rennes as dean of the faculty. He found himself in an atmosphere of jealous criticism, largely on account of his being elevated to the station of dean, and after two years of discomfort he resigned the deanship, but retained his position as a professor in the university. He secured a residence in a retired spot near a church, and lived there simply. In his leisure moments he talked frequently with the priests, and became a devout Catholic.
His contributions to science cover a wide range of subjects. In his microscopic work he discovered the rhizopods in 1834, and the study of their structure gave him the key to that of the other protozoa. In 1835 he visited the Mediterranean, where he studied the oceanic foraminifera, and demonstrated that they should be grouped with the protozoa, and not, as had been maintained up to that time, with the mollusca. It was during the prosecution of these researches that he made the observations upon sarcode that are of particular interest to us.
His natural history of the infusoria (1841) makes a volume of 700 pages, full of original observations and sketches. He also invented a means of illumination for the microscope, and wrote a manual of microscopic observation. Among the ninety-six publications of Dujardin listed by Professor Joubin there are seven general works, twenty relating to the protozoa, twenty-four to geology, three to botany, four to physics, twenty-five to arthropods, eight to worms, etc., etc. But as Joubin says: "The great modesty of Dujardin allowed him to see published by others, without credit to himself, numerous facts and observations which he had established." This failure to assert his claims accounts in part for the inadequate recognition that his work has received.
