Sachs, Julius von

views updated Jun 11 2018


(b. Breslau, Silesia [now Wroclaw, Germany, 2 October 1832; d. Würzburg, Germany, 29 May 1897)

botany, plant physiology.

Sachs was the eighth of nine children of Christian Gottlieb Sachs, an engraver, and the former Maria-Theresia Hofbauer, who were quite poor. 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. After the deaths of his father (1848) and mother (1849), he had no means of support and was forced to leave school. Sachs had met the physiologist Purkyně, who took him to Prague as his personal assistant, where his principal duties were those of draftsman. In Prague. Sachs took his final secondary school examination (1851), after which he studied at the University of Prague until 1856. The most lasting intellectual influence upon him in this period was that of the philosopher Zimmermann. 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. These papers, general treatments designed for a popular audience, were translated into Czerch and published in Purkyně’s journal Živa.

Sachs received the Ph.D. in 1856: and in the same year he attended a scientific congress at Vienna. where he met many prominent botanists. The next year he qualified at Prague—although the faculty did not wish the new subject to be taught—as a lecturer in plant physiology. Thus, Sachs, who later became the leader in the field, was the first to teach a whole course of the subject at a German university. At this time plant physiology encompassed the whole of botany except systematics.

In 1859 Sachs became assistant in plant physiology at the Agricultural and Forestry College in Tharandt, near Dresden. With Wilhelm Hofmeister, he began to edit the Handbuch der physiologischen Botanik in 1860; and the following year he became a botany teacher at the Agricultural College in Poppelsdorf, near Bonn. During these extremely productive years at Poppelsdorf he laid the foundations of all his later scientific work. Sachs succeeded Anton de Bary as professor at Freiburg im Breisgau in 1867 but left the following year to become full professor of botany at Würzburg, a post he held for the rest of his life. Except for a trip to Norway and several visits to Italy, Sachs never left Würzburg. He refused offers that followed in rapid succession from Jena (1869), Heidelberg (1872), Vienna (1873), and Berlin (1877), as well as later ones from the Agricultural College of Berlin, from Bonn, and finally one from Munich (1891) to succeed Naegeli.

A brilliant lecturer and a highly imaginative experimenter, Sachs won fellow scientists to his views through the persuasive logic of his arguments. These talents, joined with his position as leader of the rapidly developing science of plant physiology, earned him an international reputation.

Sachs received many honors. The University of Würzburg elected him rector in 1871, and in 1877 he was named privy councillor and awarded the Order of Maximilian and the Order of the Bavarian Crown. This was accompanied by a grant of personal nobility, entitling Sachs to place “von” before his name. He also received honorary doctorates from the universities of Bonn, Bologna, and London. He was, in addition, a member or 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. Many important scientists were his students or worked for a time in his institute: Francis Darwin, Goebel, Klebs, F. Noll, Pfeffer, Stahl, De Vries, S. H. Vines, and Appel.

Throughout his life Sachs displayed an enormous appetite for work. Unfortunately, the intense inner restlessness that constantly drove him to new efforts and achievements also severely damaged his health, to such an extent that the letters from the last fifteen years of his life constitute one protracted health report (Goebel). He suffered from nervous disorders and excruciating pains—probably neuralgic—accompanied by insomnia and aggravated by extensive damage to his liver and kidneys.

Like many other outstanding scientists, Sachs was often overbearing and unfair. In scientific controversies and in many letters he occasionally adopted a harsh and implacable tone—which, to be sure, was not unusual in scholarly disputes of the nineteenth century. 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. Even Sachs’s earliest independent investigations aroused general admiration and are still of value. In the course of this research on the metabolism of stored nutrients during the germination of seeds (1858–1859), he discovered the transformation of oil into starch in Ricinus seeds. His work was characterized by a combination of microscopic and microchemical methods, by means of which he provided a clear picture of the catabolism and transport of stored nutrients. Another early investigation dealt with the culture of plants in pure nutrient solution (1860).

Pursuing research begun by Liebig, Sachs solved both practical and theoretically important problems regarding the mineral requirements of plants. In this connection he discovered the corrosive action of roots on marble slabs, indicating their ability to sequester minerals (1860) and the toxicity of solutions containing a single salt. He studied the influence of temperature on life processes (1860), especially the effects of freezing. He discovered the law of “cardinal points,” according to which each vital process has a minimum, an optimum, and a maximum temperature that are mutually related.

Particularly important was Sachs’s demonstration, beginning in 1861, that the starch in the chloroplasts is the first visible product of assimilation and that carbon dioxide assimilation (photosynthesis) actually occurs in chloroplasts. These discoveries, like many others that he made, are cornerstones of modern plant physiology.

Further experiments dealt with the effect of light and, above all, with the origins of etiolation (1862) and the formation of flowers and roots (from 1865). His highly significant studies of growth and its mechanisms in roots (from 1872) and shoots led to the discovery of the “great period of growth.” Sachs also demonstrated that the formation of plants depends more on processes of cell enlargement than on those of cell division in the meristem. From about 1873 Sachs devoted increasing attention to the physiology of stimuli: geotropism, “heliotropism” (phototropism), and hydrotropism.

In his later investigations and theoretical papers. Which lacked much of the experimental ardor of the earlier ones, Sachs sought evidence for his theory earlier ones, Sachs sought evidence for his theory of “specific organ-forming substances.” This theory took as its starting point the fact that although plants can grow in the dark, they cannot form flowers there (1865). From this, he contended, it follows that specific substances necessary for the formation of flowers are produced in the leaves and that these substances are essential for this development. Sachs claimed that similar substances cause differentiation in the shoots and roots. In his last publications he gave a detailed account of this theory of “matter and form,” which was simultaneously a challenge to idealistic morphology as advocated by Alexander Braun.

Although modern plant physiology would be inconceivable without Sachs’ contributions in these areas, he was, however, less successful in dealing with certain other questions, especially those concerning the transport of nutrients and water. He stubbornly held to the theory—not original with him—that water is conducted in the cell walls of wood (imbibition theory). Insisting that the sieve tubes play no role in transporting carbohydrates, he maintained instead that the latter are transported in the form of “wandering starch.” Moreover, his great authority long delayed discovery of the real answers to these questions. Equally untenable were the attacks he made in the last years of his life against the mechanisms proposed by Darwin in his theory of evolution and against other writings of Darwin.

Sachs’s skill in experimentation was astonishing, especially in view of the rudimentary methods available when he began his research. He was constantly concerned to point out the independence of physiology from physics and chemistry: “More and more I find that physiology achieves its most important results when it goes its own way entirely, without concerning itself very much with physics and chemistry” (letter of 15 May 1879). This is not to imply that Sachs did not use chemical and physical knowledge in his research. That he did so can be clearly seen, for example, in the number of microchemical demonstration methods he used, many of which he himself devised. Further examples are his proof of the existence of starch in the whole leaf by the iodine test, still used as a lecture experiment, and the gas bubble method for demonstrating the formation of oxygen in photosynthesis, also still used in laboratory classes.

Sachs invented or at least substantially improved many of the devices that were long prominent in botany laboratories: the hanging sieve, for demonstrating hydrotropism; the root box, for making visible the growth and branching of roots; the auxanometer, for automatically recording the processes of growth: a hand spectroscope, for measuring the light absorbed through the leaves; the clinostat. for compensating for gravity; centrifuges, for experiments involving centrifugal force; and thermostats and boxes for unilateral illumination. Although much of this apparatus now appears simple, even primitive, it was revolutionary in Sachs’s day, when scarcely any apparatus other than the microscope was used. Sachs also was responsible for innovations in experimental technique, having introduced, for example, the use of seedlings in order to obtain a large number of uniform plants.

Many of the experimental papers written by Sachs and his students were published in Arbeiten des Botanischen Instituts in Würzburg. The most important were collected as Gesammelte Abhandlungen über Pflanzenphysiologie.

Sachs also exerted a major influence through his books. In Geschichte der Botanik vom 16. Jahrhundert bis 1860 he went far beyond a dry historical description, presenting with great skill the basis of his own scientific work. This masterful presentation records all the fundamental elements upon which Sachs built his many theories. His immense contribution to the subject is most clearly apparent in Lehrbuch der Botanik (which went through four editions) and in Vorlesungen über Pflanzenphysiologie (which appeared in two editions). The Vorlesungen in particular, by virtue of the freer style permitted by the lecture form, illustrates Sachs’s achievements in an especially vivid manner. The material it contains, much of which Sachs himself had elaborated, meshes harmoniously with contemporary knowledge in related branches of science and with it forms a unified whole.

Sach’s books were long the definitive works in plant physiology. Through them the results both of his own research and of that of many contemporaries, such as Hofmeister and Naegeli, became widely known. In fact, so complete was this process that it is frequently difficult to isolate Sachs’s personal contributions. The numerous illustrations in these books, the majority of which derived from Sach’s drawings, often were incorporated, without his knowledge, in the textbooks of other authors, and this practice was continued until quite recent times.

In reviewing Sach’s work it becomes clear that he was little interested in making narrow observations or in answering highly specific questions. He always sought major laws of universal applicability. Even when he failed to solve a problem he at tempted to outline a comprehensive framework which might lead to the relevant physiological aspects. To the extent permitted by contemporary knowledge, he was highly successful in this endeavor.


I. Original Works. Sachs’s writings include Handbuch der Experimentalphysiologie der Pflanzen, which is vol. IV of Handbuch der physiologischen Botanik, W. Hofmeister, A. de Bary, T. Irmisch, N. Pringsheim. and J. Sachs, eds. (Leipzig, 1865); Lehrbuch der Botanik (Leipzig, 1868, 1870, 1872, 1874); Geschichte der Botanik vom 16. Jahrhundert bis 1860 (Munich, 1875); Vorlesungen über Pflanzenphysiologie (Leipzig, 1882, 1887); and Gesammelte Abhandlungen über Pflanzenphysiologie, 2 vols. (Leipzig, 1892–1893). Sachs also edited Arbeiten des Botanischen Instituts in Würzbug. 1–3 (1871–1888).

II. Secondary Literature. See K. Goebel, “Julius Sachs,” in Flora, 84 (1897), 101–130; R. B. Harvey, “Julius von Sachs,” in Plant Physiology, 4 (1929), 155–157; P. Hauptfleisch, “Julius von Sachs,” in Münchener medizinische Wochenschrift, 26 (1897): F. Noll, “Julius v. Sachs,” in Naturwissenschaftliche Rundschau, 12 (1897), 495–496; E. G. Pringsheim, Julius Sachs der Begründer der neuen pflanzenphysiologie 1832–1897 (Jena, 1932); W. Ruhland, “Julius Sachs,” in Handwörterbuch der Naturwissenschaften, VIII (Jena, 1913), 529; and S. H. Vines, obituary in Proceedings of the Royal Society, 62 (1897–1989), xxiv—xxix.

Martin Bopp

Sachs, Julius von

views updated Jun 08 2018

Sachs, Julius von

German botanist 1832-1897

Julius von Sachs was born October 2, 1832, in what is now Poland. Although his family was very poor, his brilliance and constant hard work helped him become in his day the foremost authority on the new science of plantphysiology . He was made a member of many scientific societies and academies, and was awarded a grant of nobility that allowed him to use "von" before his name. Sachs published several books that became the definitive plant physiology references for many years. His Lehrbuch der Botanik (Textbook of Botany ) went through many editions and is still read today.

Sachs's main scientific contributions to plant science came with his early research in the mid-1800s. He enjoyed lab research more than attending lectures in school and he worked with incredible energy and determination. Throughout his career, Sachs strove to find general principles and large concepts involved in botany, rather than focus on smaller, more specific questions. He used microscopic and chemical techniques to study three main areas of plant physiology: carbon use in plants, the mineral requirements of plants, and the effect of temperature on plants. This work laid the foundation for the study of plant physiology among his successors.

In examining the fate of carbon in plants, Sachs used an iodine test to show that carbon was first accumulated as starch in the leaves of plants. He also demonstrated that this accumulation occurred in the chloroplasts and that chlorophyll, light, and carbon dioxide were necessary for carbon fixation. Sachs also observed the way in which the carbon in starch was converted into different compounds in the plant, such as oils, sugars, and proteins. He was one of the first researchers to believe that enzymes did essential work in these metabolic conversions.

Sachs developed a method to culture plants in water instead of soil, which allowed him to experiment with the nutrient content of the water he gave the plants. He used this technique to demonstrate that plants can grow with just water, the right nutrients, and sunlight. Many other scientists believed at first that he must have faked his resultsthey were certain that soil was necessary for plant growth. Later, of course, Sachs's pioneering research led to the development of hydroponics and the agricultural fertilizer industry.

Sachs's examination of the effects of temperature on plants showed that plants have minimum, maximum, and optimum temperatures at which they grow. These ideas became important later in the study of ecology.

As one of the founders of the modern study of plant physiology, Sachs developed new techniques and scientific instruments, and he helped make plant physiology into a scientific discipline with its own methods and laws. His great authority occasionally led him to be unfair in disagreeing with other scientists (including Charles Darwin) and just his disapproval of an idea could delay research into it. Despite this, Sachs made very important advances in the plant sciences and he was very well respected when he died in Germany on May 29, 1897.

see also Darwin, Charles; Hydroponics; Photosynthesis, Carbon Fixation and; Physiologist; Physiology; Physiology, History of.

Jessica P. Penney


Morton, A.G. History of Botanical Science. London: Academic Press, 1981.

Sachs, Julius von. History of Botany. Translated by Henry E. F. Garnsey. New York: Russel and Russel, 1890.

Sachs, Julius von

views updated Jun 08 2018

Sachs, Julius von (1832–97) German botanist. A founder of plant physiology, his Textbook of Botany (1868) was an influential synthesis of botanical data. Sachs demonstrated the importance of transpiration and the role of chlorophyll in plants.