THE PHYSICAL BASIS OF LIFE 263 
is usually credited with being the discoverer of protoplasm. 
His researches, moreover, were closely connected with the 
development of the ideas regarding the réle 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 con- 
struction of hydraulic work in Sédan.’’ He had already 
shown a love for natural science, and this led him from engin- 
eering into work as a librarian and then as a teacher. He 
made ficld observations in geology and botany, and com- 
menced 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 zodlogist, 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 sci- 
entific investigator that he was called to the newly founded 
University of Rennes as dean of the faculty. He found him- 
