Robert Emerson (November 4, 1903 – February 4, 1959) was an American scientist noted for his discovery that plants have two distinct

photosynthetic reaction centre A photosynthetic reaction center is a complex of several proteins, biological pigments, and other co-factors that together execute the primary energy conversion reactions of photosynthesis. Molecular excitations, either originating directly from ...

Family

Emerson was born in 1903 in

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

, the son of Dr. Haven Emerson, Health Commissioner of New York City, and Grace Parrish Emerson, the sister of

Maxfield Parrish Maxfield Parrish (July 25, 1870 – March 30, 1966) was an American painter and illustration, illustrator active in the first half of the 20th century. His works featured distinctive saturated hues and idealized neo-classical imagery. The ...

. Emerson was the brother of John Haven Emerson the inventor of the

iron lung An iron lung is a type of negative pressure ventilator, a medical ventilator, mechanical respirator which encloses most of a person's body and varies the air pressure in the enclosed space to stimulate breathing. It assists breathing when Musc ...

. He married Claire Garrison, and they had three sons, and a daughter.

Career

Emerson received a master's degree in 1929 from Harvard, and received his doctorate from the

University of Berlin The Humboldt University of Berlin (, abbreviated HU Berlin) is a public research university in the central borough of Mitte in Berlin, Germany. The university was established by Frederick William III on the initiative of Wilhelm von Humbol ...

working in the laboratory of Otto Warburg.

Thomas Hunt Morgan Thomas Hunt Morgan (September 25, 1866 – December 4, 1945) was an Americans, American evolutionary biologist, geneticist, Embryology, embryologist, and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries e ...

invited him to join the Biology Division at the

California Institute of Technology The California Institute of Technology (branded as Caltech) is a private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small group of institutes ...

where he worked from 1930 to 1937, and again for a year in 1941 and 1945. From 1942 to 1945 he worked on producing rubber from the guayule shrub for the American Rubber Company. In 1947 he moved to the Botany Department of the

University of Illinois The University of Illinois Urbana-Champaign (UIUC, U of I, Illinois, or University of Illinois) is a public university, public land-grant university, land-grant research university in the Champaign–Urbana metropolitan area, Illinois, United ...

, where he remained for the rest of his life.

Experimental results

Emerson's first "important" result was the quantification of the ratio of

chlorophyll Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy ...

molecules to oxygen molecules produced by photosynthesis. Emerson and William Arnold found that "the yield per flash reached a maximum when just 1 out of 2500 chlorophylls absorbed a quantum". Next, in 1939, Emerson demonstrated that between 8 and 12 quanta of light were needed to produce one molecule of oxygen. These results were controversial, as they contradicted Warburg who reported 4, then 3, and finally 2 quanta. This dispute was settled after the death of both men, and it is now agreed that Emerson was correct, and the accepted modern value is 8 – 10 quanta. In 1957, Emerson reported results that are now called the Emerson effect, the excess rate of

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

after

chloroplasts A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

are simultaneously exposed to light of wavelength 670 nm (red light), and 700 nm (far red light).Emerson, R. (1958) "Yield of photosynthesis from simultaneous illumination with pairs of wavelengths",

Science Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...

. Vol. 127. No. 3305,

American Association for the Advancement of Science The American Association for the Advancement of Science (AAAS) is a United States–based international nonprofit with the stated mission of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsib ...

These results were later shown to be the first experimental demonstration that there are two

s in plants.

Death

Emerson died in the crash of American Airlines Flight 320 in New York City in 1959.

References

{{DEFAULTSORT:Emerson, Robert 1903 births 1959 deaths Accidental deaths in New York (state) 20th-century American botanists California Institute of Technology faculty Harvard University alumni Researchers of photosynthesis Scientists from New York City Victims of aviation accidents or incidents in 1959 Victims of aviation accidents or incidents in the United States University of Illinois Urbana-Champaign faculty