Nicolas-Théodore de Saussure (; 14 October 1767 – 18 April 1845) was a Swiss
chemist
A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of ...
and student of
plant physiology
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants.
Plant physiologists study fundamental processes of plants, such as photosynthesis, respiration, plant nutrition, plant hormone functions, tr ...
who made seminal advances in
phytochemistry
Phytochemistry is the study of phytochemicals, which are chemicals derived from plants. Phytochemists strive to describe the structures of the large number of secondary metabolites found in plants, the functions of these compounds in human and ...
. He is one of the major pioneers in the study 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 ...
.
Biography
Nicolas-Théodore de Saussure was born into a wealthy, aristocratic, Genevan family, many of whose members were accomplished in the natural sciences, including botany.
He was the second child of
Horace-Bénédict de Saussure (1740–1799), who was an eminent geologist, meteorologist, physicist and Alpine explorer, and Albertine-Amélie Boissier (1745–1817). His great-uncle,
Charles Bonnet, was a famous naturalist whose research included experiments on plant leaves. His grandfather Nicolas de Saussure was a noted agriculturist, for whom Nicolas-Théodore was named. Nicolas-Théodore was called "Théodore" to distinguish him from his grandfather, and he published his professional papers under the name Théodore de Saussure after his father died. (While his father was alive, Théodore's papers were published under the name "de Saussure fils", as was the custom of the day for the sons of scientists having the same surname.
Nicolas-Théodore, his sister, Albertine, and brother, Alphonse, were educated at home because their father thought the educational system of the day was inferior. From 1782 to 1786, he attended the
University of Geneva
The University of Geneva (French: ''Université de Genève'') is a public university, public research university located in Geneva, Switzerland. It was founded in 1559 by French theologian John Calvin as a Theology, theological seminary. It rema ...
, where he studied math, science, and history.
During the early years of the
French Revolution he traveled abroad, meeting with eminent scientists in London. He traveled abroad again in the late 1790s, and in 1800 became acquainted with Parisian scientists and other luminaries.
While there, he took courses in chemistry and presented a paper. Upon returning to Geneva in 1802,
he accepted an honorary professorship of
mineralogy
Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical mineralogy, optical) properties of minerals and mineralized artifact (archaeology), artifacts. Specific s ...
and
geology
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth ...
at the
University of Geneva
The University of Geneva (French: ''Université de Genève'') is a public university, public research university located in Geneva, Switzerland. It was founded in 1559 by French theologian John Calvin as a Theology, theological seminary. It rema ...
. Although he taught very little, he remained on the faculty until 1835. He lived quietly and somewhat reclusively, doing research in his own private laboratory (as was the custom for scientists of his day), but, like others in his family, he was active in public affairs in Geneva,
and he served on the Genevan representative council.
Nicolas-Théodore's sister,
Albertine Necker de Saussure, was a noted early writer on the education of women. Nicolas-Théodore left no direct heirs, but he is the great-uncle of
Ferdinand de Saussure
Ferdinand Mongin de Saussure (; ; 26 November 185722 February 1913) was a Swiss linguist, semiotician and philosopher. His ideas laid a foundation for many significant developments in both linguistics and semiotics in the 20th century. He is wi ...
, an important
linguist
Linguistics is the scientific study of language. The areas of linguistic analysis are syntax (rules governing the structure of sentences), semantics (meaning), Morphology (linguistics), morphology (structure of words), phonetics (speech sounds ...
and
semiotician
Semiotics ( ) is the systematic study of sign processes and the communication of meaning. In semiotics, a sign is defined as anything that communicates intentional and unintentional meaning or feelings to the sign's interpreter.
Semiosis is an ...
.
Career
As a young man, Nicolas-Théodore accompanied his father on his
Alpine expeditions, some of them under arduous conditions, and assisted him with experiments in physics, chemistry, mineralogy, and meteorology. In one experiment, Nicolas-Théodore confirmed
Boyle's law
Boyle's law, also referred to as the Boyle–Mariotte law or Mariotte's law (especially in France), is an empirical gas laws, gas law that describes the relationship between pressure and volume of a confined gas. Boyle's law has been stated as:
...
by a new method: He carefully weighed a tightly closed flask at many different altitudes and found that the differences in weight were exactly proportional to the differences in barometric pressure readings. In other research in the physical sciences, he named the mineral
dolomite after
Déodat Gratet de Dolomieu, in March 1792.
Nicolas-Théodore was attracted to chemistry by Lavoisier's discoveries, and he adopted Lavoisier's new system of chemistry early in life.
He became interested in the chemistry and physiology of plants, including gas exchange and the ways that different soils affected their growth.
[Nash LK 1952 p. 107] His early papers on these subjects laid the groundwork for some of the chapters in his magnum opus, ''Recherches chimiques sur la Végétation'' ("Chemical Research on Plant Growth"), published in 1804.
This book was the first summation of the fundamental process 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 ...
and a major contribution to the understanding of plant physiology. In contrast to some of his predecessors in the field of photosynthesis research, Saussure based his conclusions on extensive quantitative data that he had collected.
In ''Recherches chimiques sur la Végétation'' (1804) Saussure showed that the increase in the mass of a plant as it grows could not be due only to the uptake of
CO2, but was also a result of the incorporation of water into plant dry matter. He demonstrated this by showing that plants grown with their roots in water and their shoots in an atmosphere of ordinary air with added
CO2 increased in dry weight by an amount much greater than could be attributed to the assimilation of the
CO2 gas available to them. Plainly, the weight increase had come from the water. In addition, Saussure demonstrated that plants obtain their carbon from the carbon dioxide in the atmosphere, not through uptake from
humus
In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Lati ...
in the soil, as his immediate predecessors in photosynthesis research had generally believed.
He also showed that plants require mineral nutrients, which they take up from the soil, and nitrogen, although he did not trace the source of plant nitrogen definitively to the soil.
Saussure's finding that the source of plant minerals was the soil disproved the widely held view that mineral substances in plants arose from vague "transmutations" within the plant.
His work enabled completion of the basic, overall chemical equation of photosynthesis, according to which carbon dioxide and water, in the presence of light, are converted by a green plant into fixed carbon (such as
glucose
Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae d ...
, food for the plant), with gaseous
oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
released as a byproduct. Based on his accomplishments in plant chemistry and physiology, Saussure is considered the last of the major early pioneers of photosynthesis research, completing the work begun by his predecessors, including
Jan Baptist van Helmont
Jan Baptist van Helmont ( , ; 12 January 1580 – 30 December 1644) was a chemist, physiologist, and physician from Brussels. He worked during the years just after Paracelsus and the rise of iatrochemistry, and is sometimes considered to be ...
,
Joseph Priestley
Joseph Priestley (; 24 March 1733 – 6 February 1804) was an English chemist, Unitarian, Natural philosophy, natural philosopher, English Separatist, separatist theologian, Linguist, grammarian, multi-subject educator and Classical libera ...
,
Jan Ingenhousz, and
Jean Senebier
Jean Senebier (25 May 1742 – 22 July 1809) was a Republic and Canton of Geneva#History, Genevan Calvinist pastor and naturalist. He was chief librarian of the Republic of Geneva. A pioneer in the field of photosynthesis research, he provided ...
.
For the several decades following publication of Saussure's book, his findings about the atmospheric source of plant carbon and the soil source for plant mineral nutrients were largely neglected, and little progress was made in further unraveling the chemical processes within plants. Then, Saussure's findings were re-discovered and revived by the eminent German chemist
Justus von Liebig
Justus ''Freiherr'' von Liebig (12 May 1803 – 18 April 1873) was a Germans, German scientist who made major contributions to the theory, practice, and pedagogy of chemistry, as well as to agricultural and biology, biological chemistry; he is ...
. In addition, field research by French agricultural chemist
Jean-Baptiste Boussingault
Jean-Baptiste Joseph Dieudonné Boussingault (2 February 1801 – 11 May 1887) was a French chemist who made significant contributions to agricultural science, petroleum science and metallurgy.
Biography
Jean-Baptiste Boussingault – an agric ...
substantiated Saussure's conclusions on the importance of mineral nutrients that plants take up from the soil. Saussure's findings have had a significant impact on many disciplines, including chemistry, agriculture, agronomy, soil science, plant physiology, and plant nutrition. He is considered one of the pioneers of modern agriculture.
In addition to his studies in plant physiology, Nicolas-Théodore made important advances in the analysis of organic substances. He determined the composition of
alcohol
Alcohol may refer to:
Common uses
* Alcohol (chemistry), a class of compounds
* Ethanol, one of several alcohols, commonly known as alcohol in everyday life
** Alcohol (drug), intoxicant found in alcoholic beverages
** Alcoholic beverage, an alco ...
and
ether
In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R� ...
, and studied
fermentation
Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduce ...
, the conversion of
starch
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diet ...
es into
sugar
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose
Glucose is a sugar with the Chemical formula#Molecular formula, molecul ...
s, and many other biochemical processes. In 1815 he was one of the founding members of ''Société Helvétique des Sciences Naturelles'' (
Swiss Academy of Natural Sciences).
Honours
* 1808 Correspondent of the First Class of the
French Institute.
* 1812 Member of the
Royal Institute of the Netherlands.
* 1820 Fellow of the
Royal Society of London
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, r ...
* 1820 Member of the
Bavarian Academy of Sciences and Humanities
The Bavarian Academy of Sciences and Humanities () is an independent public institution, located in Munich. It appoints scholars whose research has contributed considerably to the increase of knowledge within their subject. The general goal of th ...
.
* 1830 Foreign member of the
Institute of Bologna.
* 1837 Plant genera ''
Saussurea'' and ''
Saussuria'' are named after him.
* 1842 Elected president of the ''Congrés Scientifique de Lyons''.
Works
* ''Recherches chimiques sur la Végétation''. Chez laV.e Nyon, Paris. (Reprinted in facsimile: 1957, Gauthier-Villars, Paris; and 2010, Nabu Press
** Three translations of ''Recherches chimiques sur la Végétation'':
*** First German translation: ''Theodor von Saussure's chemische Untersuchungen über die Vegetation'' with commentary, by F.S. Voigt. Reclam, Leipzig 1805.
*** Second German translation: ''Chemische Untersuchungen über die Vegetation'' . Vols. 1&2. Engelmann, Leipzig 189
Digital editionby the
University and State Library Düsseldorf
The University and State Library Düsseldorf (, abbreviated ULB Düsseldorf) is a central service institution of Heinrich Heine University. Along with Bonn and Münster, it is also one of the three State Libraries of North Rhine-Westphalia.
...
*** English translation: Chemical Research on Plant Growth: A translation of Théodore de Saussure's Recherches chimiques sur la Végétation by Jane F. Hill, Springer Science+Business Media, New York, 2013. .
Notes
References
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{{DEFAULTSORT:Saussure, Nicolas-Theodore de
1767 births
1845 deaths
18th-century scientists from the Republic of Geneva
19th-century Swiss chemists
Swiss Protestants
Foreign members of the Royal Society
Swiss politicians
Members of the Bavarian Academy of Sciences
Members of the Royal Netherlands Academy of Arts and Sciences
Plant physiologists
Nicolas Theodore