PLANT PHYSIOLOGY

NICOLAS THPODORE DE SAUSSURE1, 67-1845

PLATE IV

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NICOLAS THEODORE DE SAUSSURE'

(WITH ONE PLATE AND THREE FIGURES)NICOLAS THEODORE DE SAUSSURE (plate IV) adopted quantitative meth-

ods in dealing with the problem of plant nutrition at a time when practi-cally all other botanists were concerning themselves with theories of thevital forces which supplied food to plants in the form of the mysterious sub-stance known as humus. DE SAIJSSURE sustained and added to the discov-eries of INGEN-Housz and SENEBIER and proved that the green parts ofplants take up and decompose a substance of the air at the same time thatthey assimilate water. His experiments on carbon assimilation are numer-ous and precise, and were presented with great perspicuity in his "Re-cherches Chimiques sur la Vegetation" published in 1804.. DE SAUSSUREfound that the decomposition of carbon dioxide by green plant parts was aprocess necessary for the continued life and growth of the plant, but inaddition he found that the carbon dioxide content of the atmosphere sur-rounding a plant might be increased, by artificial means, up to the pointwhere it actually was injurious to the plant. Large quantities of carbondioxide in the air were favorable adjuncts only if the plants were in condi-tion to assimilate rapidly. After determining the amount of carbon appro-priated by a plant, DE SAUSSURE found that the plant increased in weight byan amount out of proportion to the quantity of carbon fixed. Consequently,although he was of the opinion that the great mass of the vegetative bodywas built up from the components of the atmosphere, it was clear that a partof the vegetable mass was derived from the fixation or utilization of the soilsolution.

The family of DE SAUSSURE was of French origin but about the middleof the sixteenth century they were among the religious refugees who fledfrom France to the little Republic of Geneva. Members of the family be-came prominent in the governmental affairs of the republic, and even at thepresent time some of its members are citizens of Geneva. The DE SAUSSUREShave been interested in scientific pursuits as well as in the course of govern-ment. NICOLAS, the grandfather of NICOLAs THEODORE, was a country gen-tleman engaged in the management of his various estates and interested inagricultural matters. He published several practical treatises; on methodsof cultivation, pruning, crop failures, and soil fertility. His son, HORACEBENEDICT, who was the father of NICOLAs THEODORE, was a scientist also

1 Published with the approval of the Director of the Minnesota Agricultural Ex-periment Station as Paper no. 219 of the Miscellaneous Series.

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and we are indebted to him for many of the data on which the very founda-tions of geology rest. HORACE BENEDICT DE SAUSSURE, figure 1, was onie ofthe first and most successful Alpine travellers: perhaps he was also one of

FIG. 1. HORACE BENEDICT DE SAUSSURE, father of NICOLAs THEODORE DE SAUSSURE

the most unique, for he undertook his journeys for the sake of studyinggeology, physics, and other natural phenomena as well as for pleasure.Mountain chains, rocks, streams, glaciers, and the atmosphere were studiedso diligently that even today a large share of his work remains undisputed.He must have been ingenious as well as diligent, for he invented or perfecteda number of instruments which were required for the physical measure-ments in his work. With such a background and such an environment it isnot surprising that NICOLAs THEODORE turned his thoughts to scientificstudies. Much of the life of NICOLAs THEODORE DE SAUSSURE may be foundin "The life of HORACE BENEDICT DE SAUSSURE " by DAVID FRESIIFIELD.

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We are indebted to FRESHFIELD for the excellent portrait in Plate IV, andfor figure 2 which indicates the material environment of NICOLAs TIEODOREduring his early life.

NICOLAs THEODORE, the eldest son of HORACE BENEDICT DE SAUSSURE,was born at Geneva, October 14, 1767. The boy was educated at home for atime because his father disapproved of the educational methods of the pub-lic schools. Later, however, he attended 1'Academie de Geneve, became verymuch interested in the natural sciences, and finally became his father's as-sistant and companion. After his father's journeys ceased, NICOLAs THmO-DORE found time for his own botanical and chemical researches. The familyfortunes were sufficient to permit considerable travelling so that NIcOLAS

FIG. 2. The town house in Geneva wlhere NiCOLAs THPODORE DE SAUSSURE spent imuchi ofhis childhood.

THEODORE, as well as his father, was in direct contact with the work of for-eign scientists. The summer of 1793 he spent in England in company withdistant relatives, but late in December of that year his mother informed himof the loss of the family fortune and advised him to seek a travelling tutor-ship, for his father was no longer able to provide him with the ease to whichhe had been accustomed. Such a tutorship was not to be found, however,for the English patrons were far more interested in the classics than inscientific studies, and NICOLAS THE'ODORE returned to Geneva in the summerof 1794. He had not been home long when he and his brother were forcedto flee to Rolle on account of the great disorder in Geneva resulting fromthe effects of the revolution in France. It was in Rolle in 1794 and 1795

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that NICOLAs THE'ODORE spent a great deal of time correcting proof of thelast two volumes of his father's "Voyages." The following year he re-turned to Geneva, married RENEE FABRI, and settled down once more to hisscientific career. The treatise on carbonic acid in its relation to vegetation,

FIG. 3. NICOLAs TIdODORE DE SAUSSURE in later life as Professor of Mineralogy andGeology in the Academy of Geneva.

a prelude to his principal work "Recherches Chimiques," was written in1797. After a short interval there was more travelling so that several yearswere spent in England and in France, and the wanderers did not return to

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Geneva until 1802. At that time DE SAUSSURE received the appointment ofProfessor of Mineralogy and Geology in the Academy of Geneva. The posi-tion carried a stipend but was an honorary appointment with no regularduties; thus he was free to continue the work he had begun. His "Re-cherches Chimiques sur la Vegetation," which was published in 1804, re-ceived great attention from the scientific world, but it was a long time beforehis ideas were completely understood and appreciated. The old humustheory had such a strong hold on the botanists of Europe that DE SAUSSURE'Sexperiments were misconstrued and misunderstood until the reactionagainst the theory of a vital force set in twenty or thirty years after hispublication.

DE SAUSSURE insisted that certain minerals found in the ash of plantswere not accidental ingredients taken in with the soil water but were essen-tial to the plant as foods in spite of the fact that they were often present inextremely small quantities. He recognized the fact that in the absence ofany one of those essential elements development of the plant was impossible.He also was aware of the fact that the amount of an element was not the all-important consideration, but that a trace of one substance might be sufficientwhile larger quantities of other substances were needed.

Respiration was studied as well as carbon assimilation. Growth of theplants was impossible without respiration, and those parts in which physi-ological processes were most active required more oxygen than the parts inless active states.

NICOLAs THEODORE DE SAUSSURE was a corresponding member of theFrench Institute and a foreign member of the British Royal Society. Hewas also a member of the Societe de Physique et d'Histoire Naturelle ofGeneva. Figure 3 is taken from a portrait painted during his later life.Most of his life was spent in Geneva and it was there that he died April 18,1845. With INGEN-Housz and SENEBIER, DE SAUSSURE is responsible forfounding the modern theory of plant nutrition.-HELEN HART, Division ofPlant Pathology and Botany, University Farm, St. Paul, Minnesota.

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