VIERORDT, KARL VON

born July 1, 1818, Lahr, Baden died Nov. 22, 1884, Tbingen, Ger. German physician and professor of medicine who developed techniques and instruments for the measurement of various aspects of blood and its circulation. Vierordt studied at the universities of Berlin, Gttingen, Vienna, and Heidelberg and started a practice at Karlsruhe in 1842. His first papers, on respiration and strabismus (a visual disorder), were well received. In 1849 he became associate professor of theoretical medicine at Tbingen and four years later was made professor of physiology there. One of Vierordt's early discoveries was an exact method of making an erythrocyte (red blood cell) count. His inventions included the sphygmograph, the first instrument that could produce a graphic representation of the pulse, and the hemotachometer, an instrument that monitored the velocity of blood flow. Other research included spectrographic analyses of hemoglobin solutions, bile, and urine and studies of respiration and sound conduction.