Julius von Sachs was a German botanist from Breslau, Prussian Silesia. His experiments developed the concept of photosynthesis, and his works laid the foundation of our knowledge of microchemical methods.
Background
Sachs was born on October 2, 1832 in Wrocław, Poland. His father, Graveur Sachs, was an engraver by trade, and father taught son delineation and accuracy of line and color. From earliest boyhood Julius was fascinated with plants, making collections of them on many field excursions with his father. He gave much of his time between the ages of thirteen and sixteen to drawing and painting the flowers, fungi, and other specimens which he collected. At the Gymnasium from 1845 to 1850 he was most interested in the natural sciences, collecting skulls, writing a monograph on the crayfish. His natural science teacher, one Krober, showed a singular lack of foresight when he solemnly warned young Sachs against devoting himself to the natural sciences.
Education
From 1840 to 1845 the gifted boy attended the poorly run seminary school in Breslau and, from 1845 to 1850, the Gymnasium, where he frequently was first in his class.
Sachs took his final secondary school examination (1851), after which he studied at the University of Prague until 1856.
The botany and zoology lectures failed to hold his interest, but research that he conducted on his own led to eighteen publications on botanical and zoological topics in this period.
Sachs received the Ph. D. in 1856: and in the same year he attended a scientific congress at Vienna.
Career
In 1856 Sachs graduated as doctor of philosophy, and then adopted a botanical career, establishing himself as Privatdozent for plant physiology. In 1859 he was appointed physiological assistant to the Agricultural Academy of Tharandt (now part of the Technical University of Dresden) at Julius Adolph Stöckhardt; and in 1862 he was called to be director of the Polytechnic at Chemnitz, but was almost immediately transferred to the Agricultural Academy at Poppelsdorf (now part of the University of Bonn), where he remained until 1867, when he was nominated professor of botany in the University of Freiburg.
In 1868 he accepted the chair of botany in the University of Würzburg, which he continued to occupy (in spite of calls from more prestiguous German universities) until his death.
Sachs achieved distinction as an investigator, a writer and a teacher; his name will ever be especially associated with the great development of plant physiology which marked the latter half of the 19th century, though there is scarcely a branch of botany to which he did not materially contribute. His earlier papers, scattered through the volumes of botanical journals and of the publications of learned societies (a collected edition was published in 1892-93), are of great and varied interest. Prominent among them is the series of "Keimungsgeschichten, " which laid the foundation of our knowledge of microchemical methods, as also of the morphological and physiological details of germination. Then there is his resuscitation of the method of "water-culture, " and the application of it to the investigation of the problems of nutrition.
Most important are his experiments, developing the concept of photosynthesis, that the starch-grains, found in leaf chloroplasts, depend on sunlight. A leaf that has been in sunlight, then bleached white and stained with iodine turns black, proving its starch content, whereas a leaf from the same plant that has been out of the sun will remain white. A demonstration of this experiment is shown in the second episode of BBC Four's "Botany: A Blooming History" presented by Timothy Walker.
Sachs's later papers were almost exclusively published in the three volumes of the Arbeiten des botanischen Instituts in Würzburg (1871–88). Among these are his investigation of the periodicity of growth in length, in connection with which he devised the self-registering auxanometer, by which he established the retarding influence of the highly refrangible rays of the spectrum on the rate of growth; his researches on heliotropism and geotropism, in which he introduced the clinostat; his work on the structure and the arrangement of cells in growing-points; the elaborate experimental evidence upon which he based his "imbibition-theory" of the transpiration-current; his exhaustive study of the assimilatory activity of the green leaf; and other papers of interest.
Sachs' first published volume was the Handbuch der Experimentalphysiologie des Pflanzen (1865; French edition, 1868), which gives an admirable account of the state of knowledge in certain departments of the subject, and includes a great deal of original information. This was followed in 1868 by the first edition of his famous Lehrbuch der Botanik, by far the best book of its kind. It is a comprehensive work, giving an able summary of the botanical science of the period, enriched with the results of many original investigations. The third edition was translated into French by Philippe Édouard Léon Van Tieghem in 1873, and into English by Alfred Bennett in 1875, and published by Oxford University Press. The fourth and last German edition was published in 1874, and also issued by Oxford in 1882.
The Lehrbuch was eventually superseded by the Vorlesungen uber Pflanzenphysiologie (1st ed. , 1882; 2nd ed. , 1887; Eng. ed. , Oxford, 1887), a work more limited in scope, but yet covering more ground than its title would imply; though it is a remarkable book, it has not gained the general recognition accorded to the Lehrbuch. Finally, there is the Geschichte der Botanik (1875); a brilliant and learned account of the development of the various branches of botanical science from the middle of the 16th century up to 1860, of which an English edition was published in 1890 by the Oxford Press. As a teacher Sachs exerted great influence, for his vigorous personality and his ready and lucid utterance enabled him not only to instruct, but to fire his students with something of his own enthusiasm.
A full account of Sachs' life and work was given by Professor Goebel, formerly his assistant, in Flora (1897), of which an English translation appeared in Science Progress for 1898. There is also an obituary notice of him in the Proc. Roy. Soc. vol. lxii.
In 1885 he became foreign member of the Royal Netherlands Academy of Arts and Sciences.
Membership
He was an honorary member of many scientific societies and academies, including those of Frankfurt, Munich, Turin, and Amsterdam, as well as the Linnean Society of London and the Royal Society. Even Sachs’s earliest independent investigations aroused general admiration and are still of value.
Personality
He was extremely reserved toward those around him, including most of his students, and had close ties with only a few people. When Sachs began his scientific research, plant physiology was a totally neglected field; it became developed only through his work, which extended to nearly all branches of the subject.