From Today in Science History:
Stephen Hales (Born 17 Sep 1677; died 4 Jan 1781). English botanist, physiologist, who pioneered the quantitative experimental approach in plant and animal physiology. He was a clergyman whose work in plant physiology, Vegetable Staticks (1787), included early demonstrations of the importance of air and light in plant growth, and of the role of transpiration in causing upward sap flow. He also measured the rates of growth of shoots and leaves and the pressure roots exert on sap, and he investigated plant respiration. Hales was the first to quantitatively measure blood pressure, measured the capacity of the left ventricle of the heart, and the output of the heart per minute. He invented an artificial ventilator that could convey fresh air into prisons, ships’ holds, and granaries.
Antoine-Laurent de Jussieu (Died 17 Sep 1836; born 12 Apr 1748). French botanist who developed the principles that served as the foundation of a natural system of plant classification. He was born into a family of eminent botanists from Lyons in France. After graduating from the Jardin du Roi in 1770, he continued to work there. He is remembered for introducing a natural classification system that distinguishes relationships between plants relying a large number of characters, unlike the artificial Linnean system, which uses only a few. He distinguished 15 classes and 100 families, of which 76 remain in botanical nomenclature today. His uncles Antoine, Bernard, and Joseph de Jussieu all made important contributions to botany and his son, Adrien, subsequently continued the family tradition.