Paul Hermann Müller, also known as Pauly Mueller (12 January 1899 – 13 October 1965), was a Swiss chemist who received the 1948 Nobel prize in Physiology or Medicine for his 1939 discovery of insecticidal qualities and use of DDT in the control of vector diseases such as malaria and yellow fever. Early life and education Müller was born on 12 January 1899 in Olten, Solothurn, to Gottlieb and Fanny (née Leypoldt or Leypold) Müller. He was the oldest of four children. His father worked for the Swiss Federal Railways and the family first moved to Lenzburg in Aargau and then to Basel. Müller went to the local primary school (volksschule) and later to the lower and upper "realschule". In that time, he had a small laboratory where he developed photographic plates and built radio equipment. In 1916 he left school due to bad grades and started to work as a laboratory assistant at Dreyfus. The next year he became an assistant chemist in the scientific-industrial laboratory of the electrical plant of Lonza A.G. Returning to school in 1918, he obtained his secondary school diploma in 1919 and entered Basel University in the same year. At Basel University he studied chemistry (with a minor in botany and physics) and started to study inorganic chemistry under Friedrich Fichter. In 1922 he continued his studies in the organic chemistry lab of Hans Rupe. While working for Rupe as assistant, he received his PhD writing a dissertation entitled Die chemische und elektrochemische Oxidation des as. m-Xylidins und seines Mono- und Di-Methylderivates (The Chemical and Electrochemical Oxidation of Asymmetrical m-Xylidene and its Mono- and Di-methyl Derivatives) in 1925. He graduated summa cum laude. Early work at Geigy On 25 May 1925 Müller began working as a research chemist for the dye division of J. R. Geigy AG in Basel. His first research topics at Geigy concerned synthetic and plant-derived dyes and natural tanning agents. This work led to the production of the synthetic tanning agents Irgatan G, Irgatan FL and Irgatan FLT. In 1935, Geigy began research on moth- and plant-protection agents and Müller was specifically interested in plant protection. He said that his love for plants and nature in general, which led him to choose botany as a minor subject at university, brought him to think about plant protection. Specifically, he wanted to start synthesizing chemical plant protection agents himself. In 1937, he